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Sub-atomic Particles
Electrons - Very Light [-]
Proton - Same as Atomic no. [+]
Neutrons - Neutral [0]
Nucleas - Heavy, 99% of Mass of Atoms
Relative Mass and Relative Charge
Mass | Charge
Protons         1       |   +1
Neutrons      1        |   0
Electrons 1/1840  |  -1
Shells
1st Shell     2
2nd Shell   8
3rd Shell   8
4th Shell   18
Electrons
In an atom, the number of protons is equals to the number of electrons.

Isotopes
Isotopes have the same number of Protons but have the different number of Neutrons.

Writing of electronic configuration
Example:
Atom                         | Electronic configuration
Neon (10 electrons) | 2,8
Potassium (19 electrons) | 2,8,8,1

The periodic table of elements
Outer shell = Valence shell
Group numbers is the numbers of electrons on the outer shell.
Example: Potasium ( Group 1 ) has 1 electrons in the outer shell.
*Same group have similar chemical properties*
Group 0 are noble gases —> Full electrons on outer shell
Group 0 are also inert , unreactive and stable.
Group 1 are the most reactive because they only have 1 electrons in the outer shell which may be loss easily.

Period is the number of shell that the atom has.
Example : Hydrogen ( Period 1) has only 1 shell.

Ions
Ions are formed when an atom loses or gains electrons .
Ions can be positive and negative depending on whether the atom gains or loses.
If the atom loses electrons, the ion will be positive.
If the atom gains electrons, the ion will be negative.

Counting of Sub-atomic particles of ions
Example :
Hydrogen ion, H+ : 1 Protons , 0 Neutrons , 0 Electrons
( Must lose 1 electrons to get 1 positive for ion)
Beryllium ion, Be2+ : 4 Protons , 5 Neutrons, 2 electrons
( Must lose 2 electrons to get 2 positive for ion)
Fluoride ion, F- : 9 Protons, 10 Neutrons, 10 electrons
( Must gain 1 electrons to get 1 negative for ion)
Lose electrons = Positive charge
Gain electrons = Negative charge

Drawing the dot-and-cross diagram of ions
If they ask for “draw outermost / outer / valence shell only” draw the outer shell only.
Write down the writing electronic configuration first to be able to do it easier.

Appendix
Group 1 , 2 , 3 ‘s types of ions formed are caption ( Postively charged ions)
Example: Group 1 -> +1
Group 2 -> +2
Group 3 -> +3
Group 5, 6, 7 ‘s types of ions are Anions ( negatively charged ions)
Example : Group 5 -> -3
Group 6 -> -2
Group 7 ->  -1

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Sub-atomic Particles
Electrons are very light.
Protons is the same as atomic number.
Neutrons are neutral.
Nucleus are the heaviest sub-atomic particles in an atom.

Relative mass and charge
All sub-atomic particles has relative mass.

Electrons
Number of protons is equal to number of electrons.

Isotopes
Same number of protons but different number of neutrons.

The periodic table of elements
The group number is the number of electrons on outer shell
Group 1 is the most reactive as it has only 1 electrons in the outer shell while group 0 is noble gas so it is unreactive, inert and stable.
Period is the number of shell that the element/ atom have.

Ions
If an atom loses electrons, it will form a positive ion.
If an atom gains electrons , it will form a negative ion.

Drawing the dot-and-cross diagram of ion
If they ask for “outer shell only” draw the outer shell only.
Try to write down the electronic configuration so it is easier to draw it.

Appendix
Group 1 to 3 will form a positively charged ion ( caption )
Group 5 to 7 will form a negatively charged ion ( anion )

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Sub-atomic Particles
How light are electrons?
What is atomic number?
What do it mean by neutral?
Why is it the heaviest?

Relative mass and relative charge
Why does all sub-atomic particles have mass?

Electrons
Is all electrons is equal to Protons even outside an atom?

Isotopes
If 2 atom have the same relative mass of 7 and different number of atomic mass, 5 and 6. Are they isotopes?

The periodic table of elements
If the group number is equals to the number of electrons on the outer shell why is Group 0 called group 0 ?
What is the maximum shell an atom can goes?

Ions
How do you determine that the ion will be positive or negative?

Drawing the dot-and-cross diagram
Why does writing down the electronic configuration helps?

Appendix
Why is there no group 4 and 8?

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Sub-atomic Particles
Electrons are 1/1840 relative mass, this is how light they are.
Atomic numbers are the smaller number about of every symbol in the periodic table.
Neutrons are neutral as it has no relative charge.
It is the heaviest as it carry’s out all activities in the atom so it may need more mass to carry out?..( Guessing )

Relative Mass and Relative Charge
All matters has mass, so the sub-atomic particles has mass also.

Electrons
No, if electrons and protons are outside of an atom, they are not equal to each other.

Isotopes
No , they have different number of protons, so they are different elements.

The periodic table of elements
It is named group 0 as the outer shell of that group may not be 8.
Currently the maximum shell an atom can goes is 7 , but scientist are still trying to find out other atoms.

Ions
It depends on whether the atom loses or gains electrons lesser to be stable.

Drawing dot-and-cross diagram
When you write down the electronic configuration, it helps to let you know the number of shells you would need to draw .

Appendix
Group 4 can either gains or loses electrons.
Group 8 is already stable so it doesn’t need to lose or gain electrons.

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Drawing of electrons configuration ( Key is important!)

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Drawing of electrons configuration ( Key is important!)

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Chlorine, Cl 35/17 Cl —-> 2,8,7
Cl + ion

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Key : X = Electroms in

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Electrons configurations

Key
X-electron of li

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Sodium ion, 23/11 Na —> 2,8,1