Class for SSCC1703 - Group IIA by SHEELA CHANDREN

NUR QISTINA IZZATI BT MOHD FITRINAZRIN POON

2020-11-19 04:36:28 UTC

SUMMARY
* Alkaline earth metals is located in group 2 in periodic table.
*Form an alkaline solutions (OH) when react with H2O
*Found in earth's crust ( CO3,SO4,PO4,silicates.)
*Tend to lose 2 electrons.
*Extraction of Mg and Ca.
*Alkaline earth metal are soft but harder than alkali metal.
*Hardness are decreasing as moving down the group.
*Density and reactivity are increases when moving down the group. Melting point deceases because of metallic bonding gets weaker due to the increased size of ion
*Mg doesn't fit the trend due to the crystalline structure.
*Be is tend to form covalent molecule as Be have a small size.
*sizes of ions : superoxide > peroxide > monoxide
*Alkaline earth metal does not form superoxide.
* Compounds of Group IIA : Hydrides ,Oxides, Carbonate, Sulphate , halide -> Reactions and properties.
*Stability of oxyanion are increasing down the group because : strength of ionic bonding between cation and anion decreases, so bond strength between the atoms in oxyanion molecules increases.
* Commercial uses of limestones, CaO3
*Anomalous properties of Be. : Be salt undergoes hydrolysis to form acidic solution , compound mostly covalent because of high charge density and high polarizing power.
*Diagonal relationship of Be and Al.
* Application of metal sulphate : Epsom (MgSO4),Gypsum salt( CaSO4),BaSO4.
*Some uses of alkaline earth metals. Exp : Mg is used in flares and pyrotechnics. Sr can be found in fireworks (red flames) , Ba (BaSO4) used in paint and x-ray , Ca from (CaCO3) is a component of Portland cement.

# Thank you Dr. Sheela for today lessons.. There are actually many things that i had learnt in this topic. ,I will working hard and try to understand abut this topic.Thank you.

LIANA FAQIHAH BINTI MOHD JAFFRI

2020-11-19 04:37:22 UTC

Thankyou Dr . for today's lesson . What i got from this topic are
1 )Group 2 element known as alkaline earth metals
-Alkaline earth metal has 2 electron in s orbital
-Easily loose both electron to get stable electron configuration
- Ions are smaller that the atom they came from
2) Extraction of Mg
-Eloectrolysis MgCl2 of carnalite
-Heating Magnesite
3) Extraction of Ca
-Electrolysis of CaCl2
-Thermal reduction of quicklime from limestone
4) Physical Properties
-Alkaline earth metal are soft but harder than alkali metal
-Densities,melting point ,boiling point tend to be higher
5) Trend in Density
-As go down the group more dense (but not really perfect as magnesium has higher density than calcium)
6) Trend in melting point
-Each atom contribute 2 electron to deloocalised cloud
-Metallic bond get weaker due to increased ion
-Hence, melting point decreases
7) Trend in Reactivity
-Down the group
-Electron further away from the nucleus
-more shielding
-Size of atom increases
-Therefore, reactivity increases
8) Compound of group IIA
i) Hydrides
-Preparation ; heating element in H2 (except Be)
-Properties ; all hydrides are ionic
-Reaction ;
o with water
o thermal stabilisation
ii) Oxides
- Preparation- heating carbonates
-Physicochemical properties ;
o all metals are ionic
o down the group , melting point decreases
iii) Hydroxides
- Preparation
o Add NaOH for Be and Mg
o Othe compound add H20
- Physicochemical
o Exist as white solid
o All ionic
o down the group ,solubility increases
iv) Carbonates
-Preparation - exist naturally in earth
- Physicochemical
o solubility decreases
Thermal stability increases
v) Sulphate
-Preparation
o Reaction with metal salts with sulphuric acid
-Properties
o Thermal stability increase
o Solubility decreases
vi) Chloride
-Preparation
o For Be and Mg , add carbon and Cl2 , it will form anhydrous
o For Mg, Ca, Sr,Ba ,add HCl ,it will form hydrated
9) Relationship between enthalpy hydration and lattice energy with size ion
i) Oxides and Hydroxides
- Cation size bigger
-Anion remain same
- Hydration energy and lattice energy decreases
-The decreasing lattice energy larger than decreasing hydration energy
-So, it will have less compatible , easy to break , less energy
-Hence , solubilty increases
ii) Sulphate
-Anion size bigger
- Cation remain same
- Hydration energy decreases
-polarizing power decreases
-solubility decreases

SYED MUHAMMAD KHAIRI BIN SYED NORDIN

2020-11-19 04:37:53 UTC

Summary for group IIA
Alkaline Earth metal
-form alkaline solution when react with water and usually found in nature as compound
-have tendency to lose 2 electron
-form cation, must lose 2 electron to form stable electron configuration with +2 charge
-soft but harder than alkali metal
grey white luste in colour but form oxide coating when expose to air
-melting point decrease down the group but Mg not fit the trend as affected by crystalline structure
chemical properties
- form binary oxide when burn in O2
-form alkaline solution when react with H2O
-form ionic halide when react with halogen
Hydrates
solubility increase down the group
thermal stability increase down the group
Carbonate
solubility decrease down the group
thermal stability increase down the group
Sulphate
solubility decrease down the group
thermal stability increase down the group

NURFATINI NASUHA BINTI MOHD NAIM

2020-11-19 04:38:13 UTC

Thank you so much Dr for today's class. This topic is a little bit confusing especially for the thermal decomposition and solubility. So, here is my attempt to summarize the part that is most confusing hehehe - solubility

for oxide and hydroxide: As we go down the group, the compound is less compatible.So, it is easier to break the compound thanks to the lattice energy. Hence, the solubility increases down the group.

for sulphate and carbonate: The solubility decreases as we go down the group. The size of anion is bigger than all the cation, hence the lattice energy does not affected much by it. The decreasing in hydration energy (charge density, polarizing power) that will affect the solubility.

IFFAH IZZATI BINTI AZMAN

2020-11-19 04:38:28 UTC

Thank you Dr for today's class. This topic is little bit confusing but I will try my best to understand it. Dr, I have a question regarding the solubility. Dr, you said before about compatible size of cation and anion. Does this factor included when we want to know about the solubility increase or decrease?

The summary for today's class:
1) Polarizing the carbonate ion
- the smaller the positive ion, the higher the charge density, the greater the effect on the carbonate ion.
- when going down group, positive ion will become bigger, so the charge density is lower and less effect on the carbonate ion. The compound must be heated in order to break off the carbon dioxide.

2) Thermal decomposition
- ionic radius will increase down group, charge density of cation decrease, polarizing power become weaker, so the cation is less able to polarize the anion and less able to distort the covalent bond found in carbonate ion.

3) Polarizing power
- polarizing power increase when across the period and charge density also increases.

SYAZIEMAH BINTI JASMANI

2020-11-19 04:38:46 UTC

Thankyou Dr for your explanation.

Summary for group IIA:
-must lose both electron valence to get a stable electronic configuration.
-Going down the group the metals become more dense, the melting point become decrease and the reactivity become increases.
-All metals form ionic compound but for Beryllium it tends to form covalent molecule.
-Down the group the solubility increase while the thermal stability also increase due to the decrease in polarizing and lower lattice energy.
-Across period, the polarizing power increase because the size is smaller,charge density increase and can attract more electron.
-preparation of sulphate is reaction of the metal with sulphuric acid.
-Be have anomolous properties from other element due to the small size of Be2+
-Be can form amphoteric oxides.

HANIS SAFIYAH BINTI MOHD AMIN

2020-11-19 04:40:19 UTC

Thank you dr for the explanation today.

This are the summary for group IIA
1) the metal in this group is soft but more harder than group IA due to it have two valence electron. but it will decrease down the group.
2) the density down the group will be increase but for magnesium , it more dense than Ca because it have crystalline structure.
3) this group are strong reducing agents
4) only Ba can form peroxide and group IIA cannot form peroxide
5) for stability I still a bit confuse but for solubility, it depends on lattice energy and hydration energy. the size of anion can give difference result for the solubility down the group.

thank you again dr ^^ have a nice day

PUTERI FARISAH BALQIS BINTI ERWAN

2020-11-19 04:41:55 UTC

Summary for group IIA
Alkaline Earth Metal
-Lose both e to form stable electropositive cation
-not exist as natural elements
-Focus on Extraction of Mg and Ca
-Soft but harder than GP IA
-More dense down gp (Mg not follow)
-Reactivity increases (Mg not follow)
- The compunds -Hyride, oxides, carbonate, sulphate
-Stability of oxyanion
increases down the gp.
due to ionic bond, increas size of oxyanion.
- Polarizing carbonate ion
polarizing power strong (smaller ion)
Solubility depends on 1) LATTICE ENERGY 2) HYDRATION ENERGY

Muhammad Danish bin Mohd Arif

2020-11-19 04:53:51 UTC

Thank you Dr. for today's class and the previous video. A lot of information about this group, so I need sometime to digest it especially about the solubility. But, here are my summary on this topic.
- specific name: alkaline earth metals
- have 2 valence electron in the outermost shell
- must lose 2 electron to form stable electron configuration
- ionic radii increases down the group
- density increases going down group except Mg
- melting point decreases down the group but the trend disrupted by Mg
- the reactivity increases down the group
-extraction of Mg:
1) electrolysis MgCl2 of carnalite
2) heating magnesite
- extraction of Ca:
1) electrolysis CaCl2
2) thermal reduction
- Be and Mg give colourless compound while Ca, Sr, Ba give colour brick-red, red and yellowing-green respectively

Compounds of group iiA
- hydride
• direct heating of elements in H2 except Be
• all metals hydrides are ionic in nature except BeH2
- oxides
• all metals oxide are ionic except BeO
• melting point of the monoxide decreases down the group
- hydroxide
• all metal hydroxide ionic except Be(OH)2
• solubility increases down the group
• thermal stability increases down the group
- carbonate
• solubility decreases down the group
• thermal solubility increases down the group
- sulphate
• thermal stability increases down the group
• solubility decreases down the group
- chloride
• all metals chloride are ionic except Becl2

SITI NOR SYAFIQAH BT MOHAMAD

2020-11-19 04:56:02 UTC

Thankyou Dr for today's lesson.
This topic is so confusing to me as i still try to understand it.So i try my best to write the summary for Group IIA.
1)Group IIA is an alkaline earth metal
2)Group IIA is soft but more harder than Group IA
3)Ca more vigorous than Mg as the reactivity increase when down the group
4)Density and reactivity increase as we down the group
5)Melting/boiling point decrease as we moving down the group
6)Only Ba can form peroxide and Group IIA cannot form it.
For Part 2,its still confusing to me so i would like to ask for the further explaination about
-the polarizing power stability
-stability of oxyanion
-stability of salt
i'm sorry Dr but i try to understand it,it become more confusing to me.

Siti Hadijah binti Muslimun

2020-11-19 05:02:23 UTC

Thank you Dr for today’s lesson and pre-recorded class. I think this topic a bit confusing and a lot of things to understand but I will try my best. For a short summary from this topic is

- Group IIA known as alkaline earth metal

- Tend to lose 2 electron

- Extraction of Mg- electrolysis MgCl2 & reduction using Si

- Extraction of Ca-electrolysis CaCl2 & thermal reduction quicklime (CaO), limestone (CaCO3)

- Mg doesn’t fit the trend of melting point bcs crystalline structure

- Down the group, solubility increases. Hydration energy (less-ve) and lattice energy (less+ve) becomes smaller due to decreasing in polarizing power which is charge density and lattice energy

- Anomalous of Be

- Diagonal relationship of Be & Al

ROSE SYAZWANI BINTI RAMLI

2020-11-19 05:04:29 UTC

Thank you dr for today's class.
-name as alkaline earth metal as it form alkaline solution when react with water and it can be found in mineral from earth.
-have 2 valence electron
-easily lose 2 valence electron and form cations to became more stable
-soft but harder than alkali metals
-have grey white lustre when freshly cut
-has higher ionization energy than group IA
-strong reducing agent
-Be and Mg are colorless compound as they are stable while Ca,Sr,Br have color due to low energy of electron valence
-melting point decrease down the group but Mg has lower melting point from others as it has crystalline structure
-Be did not form ionic bond but form covalent bond due to small size and high charge density
-stability of oxyanion increase down the group as the bonding between cation and anion decrease causing the cation to attract more to oxyanion.
-increasing size of oxyanion making dissociation easier between cation and anion
-solubility decrease down the group.

CHEW ZI KHANG

2020-11-19 05:17:26 UTC

Thank you Dr. for your well-explanation about the Alkaline Earth Metals

The summary of group IIA:
- The "alkali" means that the metal will form a alkaline compound when reacting with water
- The "earth" means that this kind of metal can be found easily from the earth but not in elementary form and it is a compound(which is not soluble in water)

-Extraction of Mg is using the method of electrolysis of MgCl2 and then the product will reducing by the Si in order to get the Mg.

- Extraction of Ca is using the method of heating the lime stone in order to get quicklime and reduce by Al
- Another way for the extraction of Ca is electrolysis of CaCl2 with the help of CaF2(to reduce the melting point of the CaCl2)

-The abnormally malting point trend which is caused by the crystal structure of Mg

- Will only formed oxide and peroxide but not for superoxide due to the small size of group IIA element

-Be same as Li(from Group IA) tends to form a covalent bond with the anions due to its size and polarizability

-The solubility of the alkali earth metal salt will be based on different reasons which are lattice energy(for small anion) and solvation energy(for big anion).

- Thermal stability of the alkali earth metal salt is based on the polarizability of the cation.

- The abnormally of Be in the Group IIA( to form different type of shape of compound due to its polarizability)

- The diagonal relationship between Be and Al which will form an amphoteric oxide etc.

Lastly, I would like to thanks again to Dr. that preparing a lot of games such as Kahoot to let the class be so entertaining and enjoyable but also help us to revise all the past lecture. Thank you Dr.

Zulfa Annisa Binti Mohd Noor

zulfaa480 — 2020-11-19 05:22:51 UTC

Thank you Dr. for today's lesson and previous recorded video too . I have received a lot but still require more time to digest it .
Here is my summary on Group IIA :-
- Group IIA known as Alkaline Earth Metals . It have 2 electron valance and require to lose 2 electrons to achieve noble gases electron configuration. Alkaline earth metals cannot be found elemental state.
- There are 2 ways to extract Mg and Ca . For Mg of are electrolysis MgCl2 carnalite and heating magnesite followed by reduction using Si while for Ca are electrolysis Cacl2 and thermal reduction of quicklime (Cao) from limestone (CaCO3).
- Physical properties of Alkaline Earth Metals are soft but harder than alkali metals and hardness of alkaline earth metals decreasing down the group . It also have grey white lustre.
- Trend of alkaline earth metals in density , melting point and reactivity . The density and reactivity are increasing but melting point is decreasing as going down the group. Magnesium does not have a perfect trend as magnesium have crystalline structure.
- General properties of alkaline earth metals are they are most reactive elements except for Be due to the small size , have higher ionization energies and strong reducing agents .
- Chemical reaction with H20 , halogen , O2 , acid , reducing agents , N2 and H2
- Uses of Berrylium, Magnesium , Calcium , Strontium , Barium.
- The properties , reaction and preparation of compounds of group IIA which can be formed as hydride , oxides, carbonate ,sulphate and halide .

That's all for my summary . Thank you Dr. ! :)

SAHIZANZAIHAN BIN ISMAIL

sahizanzaihan114 — 2020-11-19 05:27:06 UTC

Summary Group IIA
- Group IIA known as Alkaline Earth Metals because it dissolves in water to produce basic solution and found in earth's crust
- lose 2 electron to be stable
- not found in naturein the elemental state

Extraction
Mg - Electrolysis MgCl2 of carnalite
- Heating magnesite, reduction using Si
Ca - Electrolysis CaCl2
- Thermal reduction of quicklime from limestone

Physical Properties
- soft but harder than Group IA
- have a gray white luster

Density and Melting Point
- the density is increased as we go down the group while the melting point is decreased
- the tren is not perfect because Mg have crystalline structure that effect the trend

Reactivity
- Increased as the size of elements increased, it is more easier to lose electron

General properties
- Be tends to form covalent bond while the others form ionic bond
- due to Be2+ has high charge density
- Be and Mg give colourless compound due to stable 2s and 3s orbital
- Ca2+ = brick-red
- Sr2+ = red
- Ba2+ = yellowish-green

Hydrides
- can be prepared directly from heating of elements in hydrogen (EXCEPT Be)
- for Be, react with LiAlH4
- metal hydrides are ionic in nature (EXCEPT BeH2)
- BeH2 is polymeric acid
- form hydoxides when react with water
- increased in thermal stabilization (down the group)

Oxides
- prepared by heating the carbonate salts
- all metal oxides are ionic EXCEPT BeO
- solubility and basicity increased down the group

Hydroxides
- react with NaOH or H2O
- all ionic EXCEPT Be(OH)2
- down the group, solubility increased (Be(OH)2 insoluble)
- down the group, thermal stablity increased (Be(OH)2 unstable)
- basicity also increased (Be(OH)2 amphoteric)

Carbonates
- most exist naturally (magnetite,lime rock)
- in lab, Mg(NO3)2 react with NaHCO3
- down the group, solubilty decreased,thermal stability increased
- stability increased because the strength of ionic bond decreased that make the
bond strength between atoms and oxyanion increased

Sulphate
- can be prepared by reaction with H2SO4
- thermal stablity increased, solubilty decreased (down the group)

Chloride
- ionic in nature except BeCl2(covalent)

Solubilty
- depends on lattice and hydration energy

oxides and hydroxides
- increased solubility
- hydration and lattice energy decrease due to the increase in cation size
- whne the size is increased, not compatible with anion, lattice energy needed decreased

sulphate abd Carbonates
- decreased solubilty
- due to less lattice energy is decreased

Anomalous Be
- High charge density
- strong lewis acid
- Greater tendencies to form complexes

HEMLYN HENDRY

2020-11-19 05:28:37 UTC

Summary of Group IIA
1.Group 2 metals are known as alkali earth metal.
2. They have 2 electrons in their s orbitals
3.Mg is extracted by electrolysis of MgCl2 of carnalite and heating of magnesite.
4. Ca is extracted by electrolysis of CaCl2 and thermal reduction of quicklime Cao and limestone CaC03.
5.Physical properties are such as group 2 metals are soft but harder than group 1 metals and the hardness decreases down the group. Densities, melting points, boiling points are higher than group 1 metals.
6.Reactivity increases down the group.
7.General properties are such as group 2 metals are most electropositive metals excepts for Be as it resembles group IIIA elements, group 2 elements have higher IE than group 1 elements, group 2 metals are strong reducing agents.
8.Group 2 metals reacts with 02 to form monoxide and peroxide(Be),reacts with h2o to form alkaline solutions, reacts with halogens to form ionic compound, reacts with acid that forms hydrogen gas and reacts with N2 and H2 to form nitrides and hydrides. It also acts as an reducing agent to obtain pure elements.
9. Group 2 metals also forms compounds such as hydrides, oxides, hydroxides, carbonates, sulphate, halides.
10. Solubility is based on lattice energy and hydration energy and thermal stability depends n charge density and polarizing ions.

Thank you for the lecture doctor and I would like to apologize for my poor explanation on the topic just now . The content is overwhelming and Ill try to understand it slowly and deeply.

WOO JOOL EONG

2020-11-19 05:55:15 UTC

Thank you Dr for the class today.

Summary for group 2:

1) 2 ways to extract the Mg:
- Electrolysis MgCl2 of carnalite
- Heating MgCO3 follow by reduction of by Si

2) 2 ways to extract Ca:
- electrolysis of CaCl2
- thermal reduction of CaO from CaCO3

3) Physical and chemical properties of grp 2 elements

4) Application of group 2 elements

5) In group 2 compound, we learned:
i) Hydride
- preparation
- reaction with h20
- thermal stabilization

ii) Oxide
- preparation
- solubility
- basicity
- melting point

iii) Hydroxide
- preparation
- solubility , basicity and thermal stability

iv) Carbonate
- preparation
- solubility, reaction with mineral acid and thermal stability
- thermal decomposition
- polarising power
- commercial use of CaCO3

v) Sulphate & chloride
- preparation
- properties
- application

6) Solubility of the size of ion

7) Anomanous properties of Be

8) Diagonal relationship of Be & Al

IRDINA AZUWIR

irdina01 — 2020-11-19 06:24:17 UTC

Summary for Group IIA
- A.K.A alkali earth metals (forms alkaline solutions & found in earth crust)
- Mg extraction: Electrolysis MgCl₂ of carnalite, heat magnasite & followed by reduction by Si
- Extraction of Ca: Electrolysis CaCl₂, thermal reduction of caO from CaCO₃
- Physical prop.: soft but harder than alkali metals, grey white lustre when freshly cut, densities & mp & bp tend to be higher than alkali metals
- Density Trend: increase down the group
- MP Trend: decrease down the group (increased of ion size)
- React. Trend: increases down the group

General Prop.
- Most reactive electropositive after GIA (except Be)
- Higher IE than GIA
- Strong reducing agent
- E°_srp Ca, Sr, Ba, about similar to alkali metals
- Similar chem. prop. with GIA
- Be & Mg give colourless compounds (stable e^- in 2s & 3s)
- Ca, Sr, Ba give colour when heated in flame (low energy of e^- valence)

Chem. Prop.
With O₂
- Form binary oxides when react with O₂- Reacts vigorously down the group
- Not form superoxide
With H₂O
- Form alkaline solutions when react with water (except Be)
- Produce gas that ignites glowing splint
With Halogen
- Form ionic halides when react with halogen
With Acids
- Forms salt and H₂ evolves when react with acid
With reducing agents
- Reduction of the oxides & chlorides of B, Ti, Zr, etc. by Mg & Ca
-N₂: form nitrides
-H₂: form hydrides

Uses
- Be: X-ray windows
- Mg: flares & pyrotechnics, flash photography, aircrafts, car engine casings, reducing agent, milk of magnesia
- Ca: reducing agent, deoxider desulphurizer decarbonizer, alloys, quicklime, Portland cement
- Sr: fireworks, potentially lightweight nuclear producing elec. (⁹⁰Sr), glass for television tubes, refining zinc, optical materials
- Ba: paint & X-ray diagnostic work (its suplhate),

Compounds
- Hydride, oxides, hydroxides, carbonate, sulphate, halide

Thermal Stability
- Increase down the group
- Smaller cation = unstable, vice versa

Solubility
- E_latt > H_hydration (insoluble), vice versa
- Oxide & hydroxide: increase down the group (incompatible sizes - E_latt decreasing greatly)
- Sulphate & carbonate: decrease down the group (decreasing hydartion energy, size compatibility ignored)

Anomaly - Be
- Small-sized ion: high charge density (favors covalent bonds)
- Strong Lewis acid
- Coordination No.:4
-Tend to form complexes
- Forms acidic solution

Diagonal Relat.
- Form covalent hydride & halides
- Amphoteric oxide
- Form carbides that contain C^4- & produced methane

SITI NAZURAH BINTI NAZARUDDIN

2020-11-19 06:24:43 UTC

Thankyou Dr for today's class. however, i still lost in solubility of oxides and hydroxide and solubility sulphate. may i ask for the keyword or the easier words to differentiate these 2 solubility?

SUMMARY group IIA
- group IIA known as an alkaline earth metals.
-Extration of Mg:

electrolysis MgCl2 of carnalite
Heating Magnesite, followed by reduction using Si

-Extraction CaCl2

Electrolysis CaCl2
Thermal reduction of quicklime (CaO) from limestone (CaCo3)

-Physical properties of alkaline earth metal are soft but harder than alkali metals. hardness decreaing down group. when exposed to air, they quicly form a though, thin and oxide coating.
-trend in tdensity, it becomes more dense down the group except for Mg who has higher demsity than Ca.
-Melting point decrease down the group except for Mg as well bcs crystalline structure can affect the mp of metal. Reactivity also increases down group.
-6 compunds of Group IIA:

Hydride, Oxides, Hydroxide, Carbonate, Sulphate, Halide

-In group IIA Be is the anomalous one due to the small size of Be2+. and always have different reaction compare to other element.

SITI RAIHANAH BINTI ROSLAN

2020-11-19 06:34:56 UTC

Summary Group IIA

- known as alkaline earth metals ; form alkaline solution when react with H2O & found in earth crust.
- not found in nature in elemental state.

extraction
Mg
- electrolysis MgCl2 of carnalite
- heating magnesite, reduction Si
Ca
- electrolysis CaCl2
- thermal reduction quicklime (CaO) from limestone (CaCO3)

physical properties
- soft but harder than alkali metal
- hardness decreases going down the group
- melting point > group IA
- reactivity increases going down the group

general properties
- 2nd most reactive electropositive element
- ionization energy > IA
- strong reducing agents
- chemical properties similar to IA but less reactive

compounds of IIA
1)Hydride
- direct heating of element in H2 (except Be)
- ionic in nature & contain H- ion (except Be)
- BeH2 covalent linked by hydrogen bridge
- reaction with water & thermal stabilization

2)Oxides
- heating of carbonate salts
- ionic (except Be)
- solubility & basicity increase going down the group
- melting point decrease

3)Hydroxide
- ionic (except Be)
- solubility & thermal stability increases down the group
- Be(OH)2 decompose to oxide

4)Carbonates
- solubility increase & thermal stability decreases

5)Sulphate
- thermal stability increase & solubility decrease

Solubility
- enthalphy of hydration > lattice energy ; salt dissolve
- lattice energy > enthalphy of hydration ; salt does not dissolve
- hydration energy becomes less -ve and lattice energy become less +ve down the group.

anamalous Be
- covalent compounds due to small size
- high charge density, high polarizing power
- undergoes hydrolysis to form acidic solution

diagonal Be & Al
- form covalent hydride & halides
- form amphoteric oxides
- form carbides and produce methane.

Thank you dr <3 for the great explanation about group IIA. it's a bit confusing but i'll try my best to understand it clearly
.
i got one question about stability of oxyanion. is it comparetible size one of the factor too?

WAN NUR ANIS FAQIHAH BINTI WAN MAT

2020-11-19 06:51:59 UTC

Thank you for the explaination but for today's part its a bit confusing and need more time for me to read through again and heard your explaination to be more clear about it but here is the summary for IIA group
-cannot be found in nature in the element state
-soft metal but harder than IA group due to the metallic bonding
-reactivity increase down the group, melting point and boiling point higher than IA group even in the same period
-Mg more dense than Ca due to the small size and electronegativity and melting point of Mg less than Ca due to crystallize structure
-Be and Mg colorless due to the stable in electron configuration (2s and 3s)while Ca(brick-red), Sr(red) and Ba( yellowish green)
-cannot form superoxide and only Ba form peroxide
all of IIA group in nature and contain hydrides except Be as Be more to covalent bonding(Be atom linked by hydrogen bridges)
-all base except BeO which is amphoteric
-most of CO3 for IIA group exists in naturally in the earth'crust due to the insoluble property of the CO3
-strength of ionic bonding between cation and anion affect the stability of oxyanion as it increased when it goes down the group
-more bigger cation size, more less effect on ion carbonate when it comes to the polarizing of ion carbonate
-higher charge density of the cation, polarizing power become decrease
-ion Mg more polarize than ion Ca due to the polarizing power as it smaller than ion Ca
-reaction with sulphuric acid Be must in oxide form, Mg in carbonate and Ca, Sr and Ba in chloride
-BeCl2 can be linear if the temperature more than 900°C
-solubility for oxide and hydroxide increase down the group as it is small anion and when it pair with big cation the incompatibility will be bigger so more energy released. the enthalpy of hydration decrease but less than lattice energy decrease
-solubility fo sulphate and carbonate decrease down the group decreased as the enthalpy of hydration decrrased.less energy released as more energy needed to break it off. compatibility between size of cation and anion didnt count as cation size will always be smaller than anion even goes down the group.
-diagonal of Be an Al such can forn covalent hydrides, amphoteric oxides and form carbide that has carbon with charge-4

1)did for IIA group, it has 2 anomaly elements since Be and Mg sometimes be different from the rest?

NURHANIS KHALIESAH BINTI MOHAMAD ZAMANI

2020-11-19 06:55:46 UTC

Thank you Dr for the class today.
Summary for Group IIA
- Also known as alkaline earth metals
- Extraction of Mg : electrolysis MgCl2 of carnalite and heatingMgC03 followed by reduction using Si
- Extraction of Ca : Electrolysis CaCl2 and thermal reduction of Ca0 from CaCO3
Physical properties
- soft but harder than alkali metal, have grey white lustre when freshly cut, densities, melting point and boiling point tend to be higher than alkali metals
- Density increases down the group
- Melting point decreases down the group
- Reactivity increases down the group
General properties
- most reactive electropositive after Group IA (except Be)
- have higher IE than Group IA
- strong reducing agent
- Be and Mg give colourless compound due to to stable electron in 2s and 3s
- Ca, Sr, Ba give colour when heated in flame
Hydride
- can be prepared by directly heating of elements in H (except Be)
- reaction with H2O
- thermal stabilization
Oxide
- can be prepared in industry and lab
- solubility increases from Be to Ba
- basicity increases from Be to Ba
Hydroxide
- all ionic except Be(OH)2
- solubility increases from Be to Ba
- thermal stability increases down the group
-basicity increases down the group
Carbonate
- solubility decreases down the group
- reaction with mineral acid
- thermal stability increases down the group
Sulphate
- thermal stability increase down the group
- solubility decrease down the group
Solubility of salt
- lattice energy >enthalpy of hydration (salt dissolve)
-enthalpy of hydration > lattice energy (salt doesn't dissolve)
-hydration energy become less -ve and lattice energy become less +ve
Anomalous Be
- small size due to high charge density
-strong lewis acid
-form acidic solution
Diagonal relationship of Be & Al
- forms covalent hydride and halide
- amphotheric acid
-form carbides that contain C22-

SITI KHADHIJAH BINTI NASIR

2020-11-19 06:55:58 UTC

Thank you, Dr for today’s class. I am still confused about the solubility. But for sure I will look back at recorded video to understand well.

Summary for Group IIA :
1.Alkaline earth metal soft but harder than alkali metal due to two valence electrons.
2.Quicklime (CaO), Limestone ( CaCO3), Slaked lime (Ca(OH)2)
3.Melting point decreases down the group except for Mg
4.The reactivity of an element increases down the group
5.Solubility depends on lattice energy and hydration energy. As the size of the ion increases, the hydration energy becomes smaller. The solubility of oxides and hydroxides is increasing as go down the group while the solubility of sulphate is decreasing as go down the group
6.Anomalous Properties of Be due to the small size of Be2+
7.There is a diagonal relationship between Be and Al. :
-Both form covalent hydride and halides
-Both form amphoteric acid

EMERALDISYAH ALIFIA WISAKSONO

wisaksono — 2020-11-19 07:26:18 UTC

Thank you for today's lecture, today was filled with so much information, I will definitely need some time to understand and digest everything. Below is my summary of the whole topic.
1. Group IIA Elements (Alkaline Earth Metals)
- 2 valence electrons
- Number of shells increases, shielding increases, atomic radius increases, & 1st IE decreases.
- Tendency to lose 2 electrons (+2 charge) to form cation (lose both electrons to get a stable electron configuration).
- Not found in nature in the elemental state.
2. Extraction of Mg
- Naturally occurring in dolomite, carnalite, magnesite.
- Electrolysis MgCl2 of carnalite (electrolyte: carnalite + NaCl, cathode: iron, & anode: graphite).
- Heating magnesite, followed by reduction using Si.
3. Extraction of Ca
- Electrolysis CaCl2 (electrolyte: CaCl2 + CaF2, cathode: iron, & anode: graphite).
- Thermal reduction of quicklime (CaO) from limestone (CaCO3).
4. Properties
- Soft but harder than Group IA (more valence electron available & hardness decreases down the group).
- Grey white luster -> when exposed to air, forms thin oxide coating.
- Densities (magnesium disrupts the trend) & melting/boiling points are higher than alkali in the same period.
- Magnesium crystalline structure affects the melting point.
- Reactivity increases down the group.
- Most reactive electropositive elements after Group IA (except Be)
- Higher IE than Group IA because higher effective nuclear charge & smaller size
- Strong reducing agents
- Chemical properties are often similar to Group IA but less reactive
- Be & Mg: colorless flame, Ca, Sr, & Ba: colored flames (easily excited)
5. Chemical Reactions
- O2; binary oxides, doesn't form superoxide.
- H2O; all react, except Be, to form alkaline solution, increasing rapidity down the group, produces ignitable gas.
- Halogen: to form ionic halides.
- Acid: more vigurous reaction down the group, H2 evolve & forming salt.
- Reducing agent: reduction of the oxides & chlorides of B, Ti, Zr, etc by Mg & Ca to obtain pure element.
- N2: form nitride.
- H2: form hydride.
6. Uses
- Be: X-ray windows
- Mg: flares, pyrotechnics, was used in flash photography, aircraft, car engine casings, missile construction, reducing agent, medicine (hydroxide, chloride, sulphate, citrate), etc.
- Ca: reducing agent, deoxidizer, desulphurizer, decarbonizer, quicklime, portland cement.
- Sr: fireworks (red), flares, glass for colored TV, refining zinc, optical materials.
- Ba: paint, x-ray diagnostic work, glassmaking, weighting agent in oil well drilling fluids, rat poison.
7. Compounds
- Hydride (MH2)
- Oxide (MO)
- Hydroxide (M(OH2)
- Carbonate (MCO3)
- Sulphate (MSO4)
- Halide
8. Carbonate
- Solubility decreases down the group.
- Reaction with mineral acids
- Thermal stability increases down the group
9. Stability of the Oxyanion
- Increases down the group; ionic bonding between cation & anion decreases=increase in bond strength between the atoms in oxyanion molecule. Increase of size causes repulsion between the atoms. Dissociation/decomposition occur if the strength between the anion & cation increases.
10. Polarizing the Carbon Ion
- The shading in the diagram shows a greater electron density.
- Positive ion attracts the delocalized electrons in the carbonate ion towards itself, the carbonate ion becomes polarized.
- Smaller the positive ion=the higher the charge density & the greater the effect on the carbonate ion.
- Going down the group, the carbonates become more thermally stable.
11. Thermal Decomposition
- Going down the group, harder to decompose.
- Carbonates, nitrates, & hydroxides -release-> CO2, NO2 & O2, & H2O (respectively).
- Smaller down the group->charge density of the cation decreases->polarizing power is weaker. Cation is less able to polarize the anion. Less able to distort the covalent bond in carbonate ion.
- Distortion weakens the covalent bond, making the decomposition easier.
12. Polarizing Power
- Smaller in size=better polarizers of carbonate ions.
13. Sulphate
- Exists in hydrated form, number of mole of hydrated water depends on the temperature.
- Thermal stability increases going down (due to decrease in polarizing ability).
- Solubility decreases going down.
14. Halide/Chloride (MCl2)
- All metal chlorides are ionic except BeCl2.
- Anhydrous MCl2 is obtained by heating the hydrated chloride salts (except MgCl2)
- Application; filling material, cement, material in bandage (MgCl2). Dehydrating agent, dust control, deicing salt (CaCl2).
15. Solubility of Salt
- Depends on lattice & hydration energy.
- Elatt>Hydration=total enthalpy will be more +ve (endothermic), doesn't dissolve.
- Elatt16. Enthalpy of Hydration & Lattice Energy Relation
- Size increase->hydration energy smaller (less -ve).
- Smaller the ion/larger charge density=stronger the bonding between the ions towards the solvent->more energy will be released (Hydration>).
- Stronger the anion bonding=more energy used to release ions from lattice crystal to gas phase (Lattice Energy>).
- Oxide & Hydroxide: Increasing solubility down the group, decrease of lattice is larger than in hydration.
- Sulphate & Carbonate: Decreasing solubility down the group, small decrease in lattice energy, large size of anion, so bigger cation + decreasing hydration energy.
17. Beryllium has some anomalous properties because of the small size. It has a diagonal relationship with Aluminum.

SITI AINA AISHAH BINTI AZIZAN

2020-11-19 08:38:48 UTC

1. Group 2A is known as alkaline earth metal
- have 2 valance electron (s orbital)
- no. of shell, sheilding effect and atomic radius will increase down the group and the ionization energy will decrease due to the atomic radius
- nuclear charge increase, so the electron farther from nucleus, so easy to loose of 2e- (form cation)
- must loose 2e- to get stable with charge +2 (electron donor)

2. Extraction
- Mg ( dissolved element, 3rd most abundance)
> 1)Electrolysis MgCl2 of carnalite
2)Heating magnasite, followed by reduction using Si
- Ca, Sr and Ba
>1)Electrolysis CaCl2 (also SrCl2 and BaCl2)
2)Thermal reduction of quicklime (CaO) from limestone (CaCO3)

3. Physical prop.
- soft but harder than alkali metals (Group 1A)
> 2 valance electrons for binding the metallic lattice together
> hardness decreasing down the group
- have gray wihte luster when freshly cut. Exposed to air, quickly form a tough, thin oxide coating

4. Trend in density
- become more dense going down the group (Mg high denser than Ca)

5. Trend in melting point
- decreasing down the group
- each atom contribute 2e- to the delocalised cloud metallic bonding gets weaker due to increased size of ion
- group 1 have lower melting point bcs each metal only contribute 1e- to the cloud
-Mg doesn't fit the trend bcs crystalline structure also affect melting point

6. Trend in reactivity
- increase down the group:
> size and no. of full electrons increase
> electron in outer shell more further from nucleus and sheilding increase (easy to loose electron)

7. General prop.
- reactive electropositive element tan Group 1A (except Be)
- higher ionization energy than Group 1A
> due to higher Zeff and smaller size
- strong reducing agent
- Esrp Ca, Sr, Ba more or less similar to alkali metal due to higher hydration energy of M2+ ion compared to the ionization energy
-chemical prop. are often similar due to alkali metal but LESS REACTIVE
- Be and Mg give colourless when burn it due to stable electrons in 2s (Be) and 3s (Mg) orbital
-halide metals give colour when heated in flame due to low energy of electron valance

8. Chem prop
- with O2
> form binary oxides
> not form superoxide
> metal is oxidised, oxygen is reduced
- with H2O
> form alkaline solution (except Be)
> produced gas that can be ignited by a lighted splint
- halogen
> form ionic halides
- with acid
> form salts and H2
- with reducing agents
> reduction of the oxides and chlorides of B, Ti, Zr etc by Mg and Ca
- N2 : form nitrides
- H2 : form hydrides

9. Compounds
- hydrides, oxides, hydroxides, carbonate, sulphate, halides

10. Thermal stability
- increase down the group
- smaller cations are unstable

11. Solubility
- depends on:
> Lattice energy
> Hydration energy (polarizability)
- when ionic substance dissolve in water:
> the separation of ions in lattice (free ions in gas)
> hydration of free ions by water
- lattice energy is greater than hydration energy (insoluble)
- oxides and hydroxides increase down the group
> in compatible sizes, lattice energy decreasing)
- sulphate and carbonate decrease down the group
> decreasing hydration energy and size compatibility has ignored)

12. Anomalous of Be
- due to small size Be2+:
> high charge density --- hidgh polarizing power --- mostly covalent
> ion is strong Lewis acid
> coordination no. --- 4
> greater tendency to form complex
> be salt undergoes hydrolysis to form acidic solution

13. Diagonal relation (Be-Al)
- From covalent hydrides and halides
- amphoteric oxides
- present of access OH ion, form [Be(OH)4]2- and [Al(OH4]- soluble
- form structure baseed o linked tetrahedra
-form carbides contai C4- and produced methane on rxn with water

Its really really confusing T_T but i'll try my best to watch again the video lecture and slowly go through about lattice and hydration and the solubility T_T Thank you dr <3 ^.^

AISYAH BINTI MASHURE

aisyahm1 — 2020-11-19 09:02:23 UTC

Thankyou Dr for the lesson today

Alkaline earth metal
1) Group IIA =
#in earth crust as carbonate, phosphates, silicates, sulfates :
#two e at s orbital
#cannot found in nature in elemental state

2)Extraction of Mg
1)electrolysis MgCl2 + NaCl (electrical conductivity, inhibit hydrolysis)
2)heating magnesite then reduction Si.

3)Extraction of Ca
1)electrolysis CaCl2/SrCl2/Bacl2
2)Thermal reduction
Limestone Caco3 >
Quicklime CaO

4) Physical Properties
✅Soft but, IIA HARDER > IA
✅Greywhite lustre ,
BUT tough, thin oxide coating
when exposed air
✅ IIA Melting point, densities boiling point > IA
5)General properties
✅2nd Most reactive electropositive exc
Be bcs tend to form covalent
1)not in chemical system
2)small size
3)high charge density
✅IE in IIA > IA
✅ Strong P[⬇️] agent
✅Be and Mg colourless?
-stable e in 2s and 3s.
✅Ca, Sr, Ba heated =colour
-low energy of e valence

6)Down group
A)Density ⬆️ exc Mg
B)melting point ⬇️
Size ⬆️,metallic bond ⬇️
exc Mg
(crystalline structure)
C) Reactivity ⬆️
- size ⬆️
- electron further from
nucleus
- shielded effect⬆️
- easy to lose e

7) Compound
🔴HYDRIDES
Preparation by Direct heating exp Be
- ionic in nature exp BeH2 (covalent)

🔴OXIDES
Preparation, heating carbonate salts,
-ionic exc BeO
- All form monoxide, exp Ba tht is peroxides (small size)
-size ion Superoxide >Peroxide >Monoxide
-Solubility ⬆️,Basicity ⬆️, Melting point ⬇️

🔴HYDROXIDE
Preparation by
+NAOH for Mg, Be
+H20 for Ca, Sr, Ba
-White solic,ionic
-Solubility ⬆️
exc BeOH insoluble
-Thermal stability ⬆️
exc BeOH unstable
-Basicity ⬆️
exc Be(OH)2 amphoteric

🔴CARBONATE
Preparation
- naturally earth crust
-Laboratory use NahCO3. Cannot Na2CO3 cause too basic
-Solubility ⬇️
-react mineral acid
-thermal stability ⬆️

🔴Sulphate
Preparation H2So4 +metal salt.
-All in hydrated form
-Thermal stability ⬆️
-Solubility ⬇️

🔴Chloride
Preparation
For Be, Mg : MO+C+Cl2
For Mg, Ca, Sr, Ba : MO +HCl
-heat hydrated chloride anhydrous exc
Mg :heat with HCl

8)Solubility
Salt dissolve -
lattice energy >hydration energy
Salt does not dissolve -
Hydration energy> lattice energy

9)relation between enthalpy of hydration and lattice energy with size ion.

a) oxide and hydroxide
-Cation size increase,
-Hydration energy and lattice energy decrease. But
-Decreasing in lattice energy > decreasing in hydration energy
-less compatible, tend to break up to separate, less energy to breakup
-Solubility increase

b) sulphate and carbonate
-anion bigger, cation same,
E-lattice energy decrease
-hydration energy decrease
-polarizing power decrease
-Solubility decrease
10)anomoly Be-small size
11)diagonal relationship Be n Al

TAN JING XUAN

2020-11-19 09:55:30 UTC

Thank you dr for the synchronous class today. I had learnt a lot of things so far and here is my summary about this chapter.
1. Alkali earth metal is called because of the element form alkaline solutions when they react with water and they are found in earth's crust.
2. Electrolysis is used to extract Mg, Ca, Sr and Br but the electrolytes are not the same.
-Mg: Electrolyte is carnalite and NaCl. NaCl is used to enhance the flow of electrons
-Ca/Sr/Ba: Electrolyte is CaCl₂ and 16% CaF₂. CaF₂ is used to decrease the m.p.
3. There is another way to extract the metal too.
-Mg: By heating magnesite then followed by reduction using Si.
-Ca/Sr/Ba: Thermal reduction of quicklime(CaO) from limestone (CaCO₃)

*** Slaked lime is Ca(OH)₂

4. Alkali earth metals are harder than alkali metals. Densities, m.p and b.p are higher than alkali metals.
5. Melting point decreases down the group due to increasing of the atomic size.

*** Mg doesn't fit the trend because of the crystalline structure.

6. All the metals form ionic compounds EXCEPT beryllium form covalent molecule.
7. All the metals are strong reducing agents.

*** Reducing agent undergoes oxidation while oxidizing agent undergoes reduction.

8. Be and Mg give colourless compounds because the energy of the flame is not sufficient to excite the electrons to higher energy level.
9. Alkaline earth metals react with o2 to form binary oxides.

***Be does not form monoxide and ONLY Ba form peroxide. All elements DO NOT form superoxide.

10. Size of the oxides: Superoxide> Peroxide> Monoxide
SIze of cations must be compatible to oxides.
11. All the metals form alkaline solution EXCEPT Be.
H₂ is formed when metal react with water. Metal reacts slowly with the water in the form of liquid and reacts rapidly in the form of vapour.
12. All the metals react with halogens to form ionic halides.
13. H₂ evolved and salt is formed when the metals react with acid.

*** For nitric acid, H₂ does not formed.

14. Anamoly of Be compounds

All metal hydrides are ionic EXCEPT for BeH₂.
All metal oxides are ionic EXCEPT for BeO.
All metal hydroxides are ionic EXCEPT for Be(OH)₂
Be(OH)₂is insoluble, thermally unstable and amphoteric.

15. Stability of oxyanion increases down the group.
16. Carbonates become more thermally stable down the group.
17. The ease of decomposition of metal carbonates, nitrates and hydroxides decreases as we go down the group.
18. -For the smaller anion (oxide and hydroxide), compability of size is important and lattice energy plays a big role in solubility. Solubility increase down the group.
- For the bigger anion (sulphate and carbonate), compability of size is not important and hydration energy plays a big role in solubility. Solubility decreases down the group.
19. Anomalous properties of Be
- small size of Be²⁺, high charge density, compound mostly covalent.
-ion is strong lewis acid
-form complexes
-Be salt form acidic solution.
20. Diagonal relationship of Be& Al.
-form covalent hydride and halides
-form amphoteric oxides
-form [Be(OH)₄]^2-and [Al(OH)₄]^-which are soluble.
-form structure based on linked tetrahedral
-form carbides and produce methane on reaction with water. Carbide react with water and produce ethyne.
Lastly, I have some questions :
1. What is meant by the melting point of alkali metal will be lower when there is only one electron contributed to the cloud? Is it because of the metallic bonding is weaker?
2. With the comparison of metal nitrates, metal carbonates and metal hydroxides, which one will be the most stable?
3. Are oxides more stable than compounds of nitrates, carbonates and hydroxides?
4. Given that the value of E_latt> H_hydration, the total enthalphy of dissolution will be more endothermic. The value of the both energy got see the negative or positive sign or not? Or just ignoring negative or positive sign and just compare the value? Does the positive and negative sign means endo or exo only? Eg: -1 > -5 or 5 > 1
Thank you dr again.

TAN SIN JOE

sjtan2000 — 2020-11-19 10:17:22 UTC

Thank you Dr.Sheela for today's lecture. This is my summary: Group IIA elements are:

Alkaline earth metal: form alkaline solutions(hydroxides) when react with water and are found in earth's crust
Strong reducing agent
Extraction of Mg: electrolysis MgCl2 of carnalite (1KCL.MgCl2.6H2O)/heating magnesite (MgCO3) followed by reduction using Si; Extraction of Ca: electrolysis CaCl2; thermal reduction of quicklime(CaO) from limestone(CaCo3)
Mg doesn't fit trend in density and melting point because of its crystaline structure
Be2+(high charge & charge density) doesn't exist due to small size(hold e-s very closely) -> tends to form covalent molecule
Higher Hhyd compare to IE, they form hydrated compound
Be & Mg form colourless compound in bunsen flame due to stable e- in 2s & 3s orbital(E of flame isn't sufficient to excites valence e-s to higher state)
Do not form superoxides due to strong reducing property: cations is too small - not easy for enough peroxide or superoxide ions to cluster around to form stable crystal lattice

DOWN GROUP:

carbonate ions are identical, charges distributed evenly with greater density concentrated on O atoms. As size cation decreases -> higher charge, cations & anions attracted more(/hold e-s more) strongly -> carbonate ion polarized -> unstable: carbonates become thermally stable increases/uneasier to decompose
solubility of oxides and hydroxides(small anions) increases: cation size increases, decrease of Hlatt is larger than decrease in Hhyd (compatibility between cation & anion increases)
solubility of sulphate & carbonate(big anion): because of large size of anion compared to cations, decrease in Hlatt doesn't significant, cation size increase, Hhyd decreases( polarization & interaction with water decreases: ions split away easier)
Anomalous: Be(has dagonal relationship with Al) - small size, high charge density & polarizing power -> tend to form covalent compound; salt forms acidic solution; coordination# = 4(form structure based on linked tetrahedra); form amphoteric oxides, covalent halides & hydrides

Here's my questions:

"Part II - stability of the oxyanion:
1.the strength of ionic bonding between cation and anion decreases resulting in the increase of bond strength between atoms in oxyanion molecule
2.the increase of size of oxyanion causes repulsion between atoms in oxyanion molecule -> decomposition occur if strength between anion & cation increases"

Is it means if cation with higher density when bonded with big oxyanion will disturb evenly distributed charges(electronegativity) hence decrease bond strength between atoms in oxyanion, increase size oxyanion thus causing decomposition to occur?

2. Part II-oxide and hydroxide: the main factor causing solubility of oxide and hydroxide increases down group is energy required to seperate the ions(Hlatt) decreases due to incompatibility between anions and cations increases; since the oxide and hydroxide anions are small anions, is the graph of compatibility increases decreases then increases again (like graph below)?

eg. will the solubility of oxide and hydroxide of Sr higher than Ba?

sjtan2000 — 2020-11-19 12:31:17 UTC

oxide and hydroxide increases down group is energy required to seperate the ions(Hlatt) decreases due to incompatibility between anions and cations increases; since the oxide and hydroxide anions are small anions, is the graph of compatibility increases decreases then increases again (like graph below)?

YEE SHI WEE

2020-11-19 14:36:19 UTC

Thank you Dr Sheela for today’s live lecture, it was really fun! :D

1. HYDRIDE compound
-Preparation: heating of hydrogen (except Be)
-BeH2: form polymeric acid (covalent)
-Thermal stability increases down the group

2. OXIDES compound
-Preparation: heating of carbonates
-Can only form normal oxide and peroxide (Ba)
-Don’t form superoxide due to incompatible
-Solubility increases

3. HYDROXIDE compound
-Preparation: Metal oxide + H2O
-Thermal stability increases (bigger size, weaker polarizing power, lower lattice energy)

4. CARBONATE compound
-Preparation: mostly exist naturally
-special name: limestone, quicklime, slaked lime, lime rock
-size of cation affects stability of oxyanion (bigger ionic size, lower charge density, weaker polarizing power, less e- attracted, harder to decompose, more thermally stable)
-solubility decrease
-thermal stability increase

5. SULPHATE compound
-Preparation: metal salt + H2SO4 -> hydrated sulphate salt
-solubility decreases
-thermal stability increase

6. HALIDE compound
-Preparation: MO + C + Cl2 -> anhydrous chloride
MO + HCL -> hydrated chloride
-BeCl2: can be in polymeric (RT), dimeric (vapor), linear (>900C)
-CaCl2: dehydrating agent

7. SOLUBILTY depends on Hlatt & Hhyd
-Hlatt & Hhyd decrease down the group (due to smaller polarizing power and lower lattice energy)
-Oxide & hydroxide: increasing solubility (1.decrease in Hlatt > decrease in Hhyd 2.They are smaller anions, bigger cations become less compatible)
-Sulphate & carbonate: decreasing solubility (1.decrease in Hhyd > decrease in Hlatt 2.They are bigger anions, bigger cations become more compatible)

8. Anomaly Be
-exhibits covalent properties
-coordination number: 4
-tends to form complexes
-form acidic solution

9. Diagonal relationship Be-Al
-form covalent hydrides and halides
-form amphoteric oxides
-form carbides with C4- and produce methane when reacts with water

QUESTIONS:
1. How to classify if an oxyanion is a big ion or small ion? Are nitrates and oxides small ion or big ion?
2. What does it meant by “GIA metals have lower melting point than GIIA metals because each metal only contributes one e- to the cloud? Isn’t the melting point of metal is affected by the nucleus charge and attraction force kah?

NURUL NASYRAH BT SAHAR

2020-11-19 14:57:10 UTC

GP IIA
alkaline earth metals,having 2 electrons on outer shell,its form cation to become stable(act as electron donor)
EXTRACTION OF MG
-electrolysis
-heating magnasite--->reductin using Si.
EXTRACTION OF CA
-electrolysis
-thermal reducion
PROPERTIES
-hardness decrease down the gp
- more dense dwn gp but trend not perfect,Mg has higher density due to crystalline structure.
-reactivity increase down the gp
-most reactive electropositive element after gp IA except Be.
-higher ionizatin energy
-strong reductin effect
-chemical propeties often similiar with alkali metals but less reactive.

COMPOUND(HYDRATE,OXIDES,HYDOXIDE,CARBONATE,SULPHATE,CHLORIDE)

HYDRIDE-all metals hydrides are ionc except BeH2 (covalent bonding)linked by hydrogen bridge.
reaction with water and thermal stability(increases down the gp)
OXIDES-solubility and basicity increase down gp,melting point (monoxide) decrease down the gp due to increasing cation size which slightly reduce lattice energy.
HYDROXIDES- increasing solubility,thermal stability,basicity dwn the gp.
CARBONATE-solubility derease down gp,thermal stability and polarizing pwer increase down gp
SULPHATE- thermal stability increase down gp due to decrease polirizing ability,solubility decreses,
CHLORIDE-all metalschlorides are ionics except BeCl2.
SOLUBILTY
-depends n lattice energy and hydration energy.
-as size ion increses hydration energy became smaller due to decreasing charge causing decrease in polarizability(more energy will be release)
ANOMALOUS PRPERTIES OF BE
-small size be2+,high charge density,high plarizing power,compound mostly covalent

tq dr fr the explaination today, even i still confuse about polarizing and solubility...but its okay i will try my best to understand and digest it :))

NUR HANISAH BT AZMAN

2020-11-19 15:49:44 UTC

Thank you Dr for the class. You kicked my adrenaline during the student's explanation session..atleast im not sleepy hehe

Summary:

· Specific name : alkaline earth metal

· Consist of 2 electron in s orbital (2 valence e)

· Extraction: only for Mg and Ca

· Mg

o Electrolysis MgCl2 of carnalite

o Heating magnesite, followed by reduction using Si

· Ca

o Electrolysis CaCl2 (and also SrCl2 & BaCl2)

o Thermal reduction of quicklime (CaO) from limestone (CaCo3)

· Physical properties

o Soft but harder than alkali metal

o Have grey white lustre

o Form an oxide coating when exposed to air

· Trend in density

o More dense down the group

o Magnesium doesn’t fit the trend (crystalline structure affect the melting point)

o Except for magnesium which have higher density than calcium

· Trend in melting point

o Decrease down the group

o Higher melting point than group 1

· Treng in reactivity

o Increase down the group

· General properties

o Most reactive electropositive element after group 1

o Except for Be which resembles IIIA elements

· Chemical properties

o O2, H2O, acid, reducing agent(B, Ti, Zr,), N2, H2 and Halogen as agent

· Uses of group IIA element

o Be : X-ray window

o Mg : flash photography

o Ca : reducing agent for preparation of metals

o Sr : fireworks

· Compound of group IIA

o Hydrides

o Oxides

o Hydroxide

o Carbonate

o Sulphate

o Halide

· Physicochemical properties

o Exist as white solid

o All ionic

o Solubility increase down the group

o Thermal stability increase down the group

o Basicity increase down the group

AHMAD IMRAN BIN AHMAD BASRI

ahmadimran — 2020-11-19 16:32:36 UTC

Thank you Dr for the class today. My summary for group 2 alkaline earth metals with be: 1. Introduction -Form alkali solution when reacted with water and can only be founded in earth crust -It has 2 valence electron and need to lose 2 electron to have a stable electron configuration -It is not found it elemental state which means it will on be in compound 2. Extraction of Mg: -Electrolysis MgCl2 of carnalite -Heating magnesite, followed by reduction using Si 3. Extraction of Ca: -Electrolysis CaCl2 -Thermal reduction of quicklime(CaO) from limestone(CaCO3) 4. Physical properties of alkaline earth metals: -They are soft but harder than alkali metals -They quickly form an oxide coating when exposed to air -The density, melting points and boiling points increase down the group 5. Trend in density: -Increase down the group -Magnesium is different because of the crystalline structure affecting the melting point) 6. Trend in melting point: -Decrease down the group 7. Trend in reactivity: -Increase down the group 8. Uses of Group 2 9. Compounds of group 2: -Hydrides -Oxides -Hydroxide -Carbonate -Sulphate -Halide 10. Physicochemical properties M(OH)2: -Exist as white solid -All ionic except Be(OH)2 -Solubility increase down the group -Thermal stability increases down the group -Basicity increases down the group 11. Physicochemical properties MCO3: -Solubility decreases down the group -Reaction with mineral acids -Thermal stability increase down the group 12. Stability of oxyanion increases down the group 13. Sulphate and it properties 14. Chloride and it properties 15. Solubility of salt 16. Anomalous properties of Be 17. Diagonal relationship of Be & Al

Ch'ng Zi Long

2020-11-20 00:06:55 UTC

Thank you dr for teaching group 2 element. Below is my summary:
1) Extraction and properties of group 2 element.

2) Chemical properties
- react with O2, H2O, halogens, acids, N2 and H2

3) Uses

4)Compounds(hydride, oxides, hydroxide, carbonate, sulphate and chloride)
- preparation
-chemical reaction
- properties

5)Thermal stability

6)Solubility

7) anomalous of Be and its diagonal relationship with Al

SITI MASYITHAH BINTI MOHAMAD JAN

2020-11-20 03:29:49 UTC

Thank you Dr for your well and detailed explaination. Here is my summary about group II :

1) Group II have two valence elactron and also known as alkaline earth metals
2) Preparation of carbonate of group IIA in lab
3) Physicochemicals properties :
# solubility decreases by going down the group
# reactivity with minerals acid
# thermal stability
4) Stability of oxyanion increases down the group due to strength of ionic bonding between cation and anion.
5) The compounds which are hydride, oxides, hydroxides, carbonate, sulphate, chloride.

Muhammad Akmal Aqil Bin Roziman

2020-11-20 08:11:03 UTC

Thank you Dr for the detailed explanation in your video and live lecture.

1) Group IIA are commonly known as alkaline earth metals.
2) As going down the group, the reactivity increases while the melting point of the group decreases.
3) Calcium Oxide is a key ingredient in making cement while beryllium is used in x-ray windows.
4) There are 6 types of compound group of Group IIA, hydrides, oxides, hydroxide carbonate, sulphate and halide.
5) Beryllium has anomalous properties compared to most metals in group IIA.
6) Beryllium is the only group IIA that forms covalent bond and forms an acidic solution when reacts with water.

NAURAH AFNAN BINTI KAMARUDIN

2020-11-20 10:31:43 UTC

Thank you for the explanation Dr.Sheela.My summary for group 2:
1)Down the group(the atomic size increase,shielding increase,ionization decrease)
2)PHYSICAL PROPERTIES
-soft but harder than gp 1
-densities,melting and boiling point higher than gp 1
3)Most reactive (except Be)
-diamagnetic,colourless)
-gp 2 increase IE than gp 1
-due to strong reducing agent
-Be and Mg give colourless due to stable electron in 2s(Be) and3s (Mg)orbital
-Ca,Sr,Ba give colour
3)HYDRIDE
-Heating in H2(except Be)
4)OXIDE
-Heating carbonate salt M=Mg,Ca
-All metal oxide ionic(except Be)
5)HYDROXIDE
-all ionic(except Be(OH)2)
-Be(OH)2 decomposed to oxide
6)CARBONATE
-NaCO3 too basic compared to NaHCO3
-MgCO3 REACT WITH NaHCO3
while CaCO3 react with Na2CO3
7)SULPHATE
-reaction metal salt with sulphuric acid
-exist in hydrated form
8)HALIDE
-all metal chloride are ionic except berilium chloride i
9)Diagonal Be and Al
-form covalent hydride and halide
-form amphoteric oxide.

Alvin Imran Bin Aziz

2020-11-20 13:20:39 UTC

Thank You for the detailed explanation Dr.Sheela. My summary for Group IIA.

1) Group IIA is usually called Alkali Earth Metal. And they have 2 Valence Electron.
2) It is very soft but is harder when compared to alkali metal(group IA)
3) It is very reactive but less reactive than Group IA
4) Going down the group, the reactivity increase because valence electron because attraction between v.electron and nucleus increased.
5) There are 6 types of compounds in Group IIA. Hydride, oxide, hydroxide, carbonate, sulphate, and halide.
6) Be have some anomalous properties when compared to other element in group IIA due to the small size of Be2+
7) Be and Al have Diagonal Relationship, some of the similarity is both form amphoteric oxide while other Group IIA will form basic oxide.

Low Jin Wei

2020-11-21 12:11:49 UTC

Thank you dr Sheela for the well and excellent explanation
Summary :
1) Group IIA is Alkali Earth Metal.They have two valence electrons in the outer shell.
2) their reactivity will increase as go down the group.
3) We got six types of compounds in Alkali Earth Metal which are Hydride,oxide,hydroxide,carbonate,sulphate and halide.