Why oxygen is a divalent?

Answer 1

'Divalent' means that an atom has the ability, and the tendency to carry two electrical charges. These are, in the case of atoms, always electrons. So, oxygen can carry two electrons.

To understand why Oxygen is divalent, we need to know how electrons 'stack-up' in an atom.

Electrons are pictured as flying in orbits around the centre of the atom, the nucleus. The pictures make it look as if they are planets plying around a sun. However, when things are as small as electrons, extra rules apply to what they can do that don't apply to big things like planets or even tennis balls.

Electrons stack up above the nucleus as they fly around, like cars in a multi-storey car park. The first parking layer has only two spaces, the next has eight, as does the third layer. This is true for all atoms. These layers of parking spaces are called electron 'shells'.

Oxygen has eight electrons to stack up. This means that it can have two in its first shell, and six in the next. It has two spaces in it's second shell.

Another rule for atoms is that they 'like' to have full shells.

This means that the Oxygen atom finds it easy to pick up two extra electrons. This means it has a tendency to grab two electrons and carry them around, making it 'divalent'. It uses these two electrons to make bonds with other atoms, so being divalent controls the kinds of bonds that it will make, the number of atoms it can bond to and so the different compounds that can be formed with oxygen.