~Hydrogen resemblance with alkali metals due to electronic configuration, electropositive character (H+) and also oxidation state (+1).

~Hydrogen resemblance with halogens because of electronic configuration, non-metallic character, exists as diatomic molecules, formation of similar compounds and oxidation state (-1)

*oxidation state of hydrogen is -1 when it binds to a more eletropositive element*

 

Hydrogen can be prepared by:
1. reaction of metal (Zn, Fe, Cu)

2. Electrolysis of water (H2 is collected at cathode)

3. Stem reforming process (cheap but produced CO,CO2 and greenhouse gases)

 

Hydrogen is used for:

1. Production of NH3 (Haber process)

2. Methanol production

3. Production of margarine (from unsaturated→ saturated)

4. Production of metals (act as reducing agent, itself undergoes oxidation)

5. As fuel (release high energy during combustion)

 

Hydrogen has small size, so

1. Can form shorter and stronger covalent bond. *shorter bond length, higher bond energy, stronger bonding*

2. Can show intersititial hydrides with lanthanide and actinide.

3. Can form bridging hydrogen bonding.

 

Hydrogen bond

1. Form strong hydrogen bond with highly electronegative atom (F>O>N). Therefore, melting&boiling point of NH3, HF, H2O is very high.

2. Hydrogen bonding causes ice to have open crystal structure, which allow it to float in water.

3. Polar molecules can soluble in water because they can form hydrogen bond with water molecules.

4. Causes unexpectedly high molecular weights (for example: carbocylic acids are dimeric due to hydrogen bond).

 

Compounds of hydrogen

1. Ionic hydride (saline hydride)- when hydrogen bonded with highly electropositive elements, itself becomes H-.

2. Covalent hydride- when hydrogen bonded with non-metal element, itself becomes H●/H+.

3. Nonstoichiometric hydrides (intersitial compounds)- when bonded with transition metals, the bonding is considered metallic.

-  Electronic configuration, Electropositive character (H+), Oxidation state (+1)

b) Resemblance with Halogens

- Electronic configuration, Non-metallic character, Diatomic molecules, Formation of similar types of compounds, Oxidation state (-1)

 

2. Preparation of H₂

a) In laboratory: 

- Reaction of metal (Zn, Fe, Cu) with diluted acid

- Electrolysis of water: H₂ is collected at cathode

b) In industry: Steam Reforming Process using hydrocarbon or coal

- IMPROTANT STEPS: Steam Reforming & Water Gas Shift
- Cheap but produce CO, CO₂ & Greenhouse gases

 

3. Uses of H₂

a) Haber Process (produce NH₃)

b) Methanol Production

c) Production of margarine

d) Production of metals (reduction)

e) As fuel

 

4. Special Properties of H₂

a) Due to small size, H₂ form covalent bond with other element except very electropositive metals (the shorter the bond length, the stronger the covalent bond)

b) Form hydrogen bonding with F, O, N

- NH₃, HF, H₂O has higher melting/boiling point because more energy/heat is needed to break down the hydrogen bonds

 

5. Effect of Hydrogen Bond

a) Unexpectedly high molecular weights

- Carboxylic acids are dimeric due to hydrogen bond

b) Density of the solid is less than the liquid

- Ice float in water due to its open crystal structure

c) Solubility

- Ionic or polar molecules dissolve in water because they can form hydrogen bond with water molecule

- Non polar molecule insoluble in water

 

6. Compound of Hydrogen – HYDRIDES

a) Ionic Hydride (H-)/ Saline halide: Compound of H bonded to highly electropositive elements

b) Covalent Hydride (H•, or H+): Molecule (e.g. H₂O), Compounds of H with non-metal element

c) Nonstoichiometric hydrides (interstitial compounds): Metallic, Compound of H with transition metals 

 

1) Hydrogen is a colourless gases, does not smell, tasteless and does not dissolve in water.

2) Hydrogen is resemblance with Group IA by

I. Electronic configuration.

II. Electropositive character

III. Oxidaton state: +1

3) Hydrogen also resemblance with Group VIIA BY

I. Electronic configuration

II. Atomicity

III. Non-metallic character

IV. Formation of similar types of compounds

V. Oxidation state:-1

4) Hydrogen can be prepared by laboratory method which hydrogen is collected with the reaction between metal an diluted acid(replacement of water). For industrial method, the process is ‘ Steam Reforming Process’ using hydrocarbon or coal. 

5) Hydrogen has 3 types of compounds.

I. Ionic Hydride/ saline hydride: H bonded to highly electropositive metals (alkali metal and alkali earth metal) except Li. Be and Mg due to samll size and high charge density of ions.

II. Covalent hydride: H bonded with non-metallic element. Solid water= ice; density gradually decrease ( hexagonal structure with open space. Less dense than liquid of water.

III. Interstitial Hydride(metallic): H bonded with transition metal. Due to smaller size of Hydrogen, it can be located in regular interstices between the metal (Hydrogen storage).

6) Industrial product of Hydrogen:

I. Production of NH3 (Haber process

II. Production of methanol

III. Production of margerine

IV. Production of metal by reduction process

7) During chemical reaction. Hydrogen can lose electron, gain electron and share a pair of electron(covalent bod)

8) 7  Reaction of Hydrogen:

I. Combustion

II. Reducing agent: reduce oxide of weak electropositive metals

III. React with more electronegative element

IV. React with more electroposistive elements- forming hydride

V. Homolytic dissociation

VI. Heterolytic dissociation

VII. Radical chain reaction

For this topic, I’ve watched the lecture video three times before I written this summary since I have to understand all of this topic and probably trying to remember all the reaction and equations involved.

Thank you Dr. Sheela for the helpful explanation during lecturer and materials provided on e-learning.

***CHARACTER: lightest &  least dense gasses, (H2+O2=explosion), produced from CH/H2O, very low mp&bp, oxidation state (±1)

***

Resemblance with group IA : 

1)Electronic configuration - ……………ns¹

2)Electropositive character & oxidation state – (+1)

Resemblance with group VIIA

1)Electronic configuration – 1s¹/ …….ns²np⁵

2)Non-metallic character

3)Atomicity – Diatomic (~Cl_2, Br_2, etc.)

4)Formation similar type of compound 

  - Halides: CCl₄, SiCl₄, GeCl₄

  - Hydrides: CH₄, SiH₄, GeH₄

5)Oxidation state – (-1)

 

***PREPARATION 

1)In lab

i)    Metal (Zn, Fe, Cu) + diluted (aq) acid

ii)   Electrolysis of H₂0 (H⁺ needed, H₂ produced at CATHODE)

2)In industry – steam reforming process

 ***USES: production of `ammonia (Haber), methanol (steam reforming), margarine, metals`, fuel

***SPECIAL PROPERTIES: lose, gain & share electron (+1, -1, covalent)

----Reaction of Hydrogen

1)Combustion: (H₂ + O₂ = H₂O) & release energy (-ve KJ)

2)Reducing agent: go through oxidation, reduce O.N (ex: +4 to +2)

3)H + more electronegative element: (H₂ + Cl₂/F₂ = HCl/HF)

4)H + more electropositive element: from H₂(0) into H (-1)

5)Homolytic dissociation: H₂ to 2H

6)Heterolytic dissociation

7)Radical chain rxn

----Due to small size : form shorter and strong covalent bond (except very electro +ve metal), form interstitial hydride with transition metal ( nombor bukan integer), form H₂ bond

 

***HYDRIDES

1)Ionic/Saline hydride: ( H bonded to group IA/IIA)

2)Covalent Hydride:  

  i)H + non-metal (14/15/16/17) = (neutral/basic/acidic/strongly acidic) (XH₄, XH₃, XH₂, XH)

  ii)Hydridic, complex compound (ionic + covalent bond)

3)Nonstoichiometric hydrides (interstitial compounds) : H + transition element

 

 

Hydrogen can be prepared in lab/industrial.

In Lab:

·         Reaction between metal and diluted acid

·         Electrolysis of water.

In Industrial:

·         Steam Reforming Process

 

Hydrogen is commonly used in 

·         Production of Ammonia, NH3 through (Haber process)

·         Production of Methanol

·         Production of margarine

·         Production of metal

Hydrogen (H) is capable to lose, gain or share a pair of electrons with another atom to form covalent bond when it is chemically reacted.

These are the reactions of Hydrogen.

·         Combustion

·         Redox reaction (Reducing agent)

·         Forming hydrogen ion

·         Forming hydride

·         Homolytic dissociation

·         Heterolytic dissociation

·         Radical Chain Reaction

Hydrogen has its special properties due to its small size.

It can form an attractive force called “Hydrogen bond” when it is coupled with atom that is highly electronegative (F,O,N) .

Elements that contain hydrogen bonding will have a higher molecular weight, lower density when it is in a solid state like ice and water (H2O) as well as their higher solubility in water (ionic/polar molecules). 

Hydrogen-Hydrides

·         Ionic Hydrides/Saline Hydride

·         Covalent Hydride

·         Nonstoichiometric Hydride

-        Colourless, oddorless gas, does not dissolve in water. 

-        Lightest element

-        Diatomic gas, dihydrogen 

-        3^rd Most abundet element found in (H2O) (element in animal and plant) (element in stars, sun) 

-        Produced hydrocarbon or water 

Position hydrogen 

1)     Hydrogen can be placed in group 1 (IA) because

-        Valence electron is 1 (1s1)

-        Electropositive character (H+)

-        Oxidation state : +1

2)     Hydrogen also can be placed in group (ViIIA) because

-         Nearest noble gas configuration

-        Non metallic element (same as noble gas)

-        Diatomic molecules (F2, Cl2, Br2,)

-        Form similar type of compound (CCl4&CH4. SICL4&SIH)

-        Oxidation state : -1 (Na+,H-)=NaH

Preparing Hydrogen :

1)     Metal (Zn,Fe,Cu) + diluted acids(aq) will form Hydrogen 

2)     Electrolysis of H2O hydrogen is obtained in cathod

3)     In industry (4 steps) obtain hydrogen by “STEAM REFORMING PROCESS” using hydrocarbon will form syn gas or water gas (co +H2)

-        Advantage ; cheap, affordable

-        Drawback; CO, CO2 and effecting greenhouse 

Hydrogen uses in industry :

1)     Production of Ammonia by Haber Process, forming fertilizers,plastics

2)     Production of Methanol (liquid) by steam reforming , 

3)     Production of Margarine, by Hydrogenation of unsaturated oil

4)     Production of Metal by reduction (oxidation number decreases) 

5)     Fuel 

Special properties of Hydrogen possibility

-        Can lose electron become H+

-        Can gain electron become H-

-        Can share electron with others and form covalent bond

Reaction of Hydrogen 

-        Combustion : Release high energy & heat (used in welding, fuel and bomb (explosive) 

-        Uses as reducing agent : Reduce oxide from weal electropositive metals such as Pb, Ni, Co, Mn

-        React with electronegative elements : Cl2 , F2. 

-        React with electronegative elements ; Na, Li forming hydride 

-        React as homolytic dissociation 

Hydrogen is the smalles in sizing it can; 

- Form shorter and stronger covalent bond. 
#shorter bond
#higher bond energy 
#stronger bond

- form intersititial hydrides with lanthanide and actinide.

- form bridging hydrogen bonding
Polar molecules can soluble in water because they can form hydrogen bond with water molecules

Hydrogen bonding is a special type of dipole-dipole attraction between molecules, not a covalent bond to a hydrogen atom. It results from the attractive force between a hydrogen atom covalently bonded to a very electronegative atom such as a N, O, or F atom and another very electronegative atom.