How Atoms
Form Ions
How Atoms form Ions
• An ion is an atom that has a charge
• The amount of protons and neutrons in an
atom are always the same.
• Atoms have the ability to lose or gain
electrons.
• If an atom gains an e- it will have a charge
of -1.
• If an atom loses an e- it will have a charge
of +1.
Why Do Atoms form Ions?
• All atoms want to be stable.
• To become stable they want t have a full
outer/valence shell.
• To decide if an atom will gain or lose
electrons, think of the easiest way for it
to get a full outer shell.
• We can draw a Bohr diagram of the ion
formed for various atoms.
e.g. Lithium
Lithium Atom
Lithium Ion
1+
3p+
4n
3p+
4n
1+
Li
Li
We write the symbol for the
Ion Li+
e.g. Oxygen
Oxygen Atom
Oxygen Ion
2-
8p+
8n
8p+
8n
2-
O
O
We write the symbol for the
Ion O2-
Ion Formation
• Worksheet page 15
• Let me know if you need help.