C.1 Atomic Structure

The energy shells are arranged around the nucelus, like layers of an onion.

The lowest energy shells is located on nearest to the nucleus.

The first and lowest shell eergy level can hold up to 2 electrons.

The second can hold upto 8.

Once there are 8 in the third shell, the fourth begins to fill up.

To save drawing atoms all the time, you could just write how many electrons there are in each energy level.

All atoms in the groups of the periodic table will have the same number of electrons in the last shell.

The chemical properties of an element depend on how many electrons it has. The way an element reacts is determined by the number of in its highest energy level. 

Because of this they all react in a similar way.

The elements in Group 0 are called noble gases.

They are very unreactive, their atoms are very stable because their arrangement of atoms means that they have full outershells.

(Except Helium)