Chemistry C3 Revision Notes - OCR Higher

THE ATOMIC STRUCTURE

Proton + 1
Neutron 0 1
Electron - 1/2000

Atoms are neutral

Isotopes
-atoms of the same element with a different mass

For every 4 atoms of chlorine, 1 is heavier.

What makes atoms reactive?
-They want to obtain a full outer shell.

<---Shared Pair of electrons from each Hydrogen atom.

H-H or H2

<--Sharing of electrons between two Hydrogen molecules and one oxygen, to make water.

H-O-H or H20

<--- Sharing of electrons between 4 hydrogen atoms, and one carbon atom, creating methane.

CH4 or H
|
H - C - H
|
H

<--- In Oxygen a double bond is used (the sharing of two pairs of electrons)

O2 or O=O

GROUP 1 METALS - ALKALI

Li - Lithium
Na - Sodium
K - Potassium
Rb - Rubidium
Cs - Caesium

They increases in size (mass) as you go down the group.
Eg. Caesium has a bigger mass than lithium.

As they increase in…