How do valence electrons work?

1 Answer
Apr 30, 2014

Lets take the ionic formula for Calcium Chloride is CaCl2

Calcium is an Alkaline Earth Metal in the second column of the periodic table. This means that calcium s2 has 2 valence electrons it readily gives away in order to seek the stability of the octet. This makes calcium a Ca+2 cation.

Chlorine is a Halogen in the 17th column or s2p5 group.
Chlorine has 7 valence electrons. It needs one electron to make it stable at 8 electrons in its valence shells. This makes chlorine a Cl1 anion.

Ionic bonds form when the charges between the metal cation and non-metal anion are equal and opposite. This means that two Cl1 anions will balance with one Ca+2 cation.

This makes the formula for calcium chloride, CaCl2.

For the example Aluminum Oxide Al2O3

Aluminum s2p1 has 3 valence electrons and an oxidation state of +3 or Al+3
Oxygen s2p4 has 6 valence electrons and an oxidation state of -2 or O2

The common multiple of 2 and 3 is 6.
We will need 2 aluminum atoms to get a +6 charge and 3 oxygen atoms to get a -6 charge. When the charges are equal and opposite the atoms will bond as Al2O3.

I hope this is helpful.
SMARTERTEACHER