What is the chemical formula for an ionic compound of potassium and oxygen?

1 Answer
Jan 24, 2017

Answer:

Potassium oxyde, #K_2O#.

Explanation:

The last level of the electronic structure of oxygen is #2s^2 2p^4#. That means that there are two electrons in the #2s# orbital, two other electrons (paired) in one of the #2p# orbitals and the remaining two (unpaired) electrons placed one in each of the remaining #2p# orbitals.

This means that oxygen has two semi-occupied orbitals and, following the octet rule, will try to capture two more electrons to complete its structure and acquire that of a noble gas. That is, when it acts to form ionic bonds, oxygen acquires structure #2s^2 2p^6# in its last level, forming the ion oxygen (2-): #O^{2-}#.

On the other hand, potassium is an alkali metal whose last level occupied is #4s^1#. That means that it will have a lot of tendency to lose that solitary electron and thus to form ionic compounds in which it takes the form of cation #K^+#.

Therefore, the binding of oxygen and potassium will give rise to an oxide of ionic character and #K_2O# stoichiometric formula.