1. A substance that is made of only one sort of atom is called an element
Elements O C C C O O O C C C O O C C C O O
Eg, Carbon is made up of
only carbon atoms
Eg, Oxygen is made up of
only oxygen atoms
A substance that is made of only one sort of atom is called an element

2. The Periodic table
There are about 100 different elements which are shown on the periodic table
Metals appear on the left and middle part of the table.
Non metals appear on the right hand side of the table
The groups contain elements with similar properties

3. Atoms Particle Mass Charge Proton Neutron Electron 1 +1 1 1 -11 -1
Atoms have a small central nucleus, which is made up of protons and neutrons, around which there are electrons

4. Label the atom
Atoms have no electrical charge because the number of positive particles (protons) is the same as the number of negative particles (electrons) so they cancel each other out! Eg, Be: 4 protons (+4); 4 electrons (-4) = 0 charge (neutral)

5. Mass number and Atomic number
Number of protons + Number of neutrons 9
Atomic Number =
Number of protons
Number of electrons 4
Beryllium has: 4 protons 4 electrons How many neutrons?

6. Electronic structure
1st shell holds a maximum of 2 electrons
2nd shell holds a maximum of 8 electrons
3rd shell holds a maximum of 8 electrons
Each level/shell has a maximum number of electrons it can hold
Electrons will fill the levels nearer to the nucleus first
This is and atom of Argon, it has an electronic structure of 2,8,8

7. Group 1 – Alkali metals
Elements in the same group in the periodic table have the same number of electrons in their highest energy level (outer shell)
which gives them similar chemical properties
Alkalis metals react strongly with water and oxygen

8. Noble gases - Group 8 elements
Noble gases are unreactive because their atoms have stable arrangements of electrons
They have eight electrons in their outer energy level – except for Helium, which only has 2 electrons