Which is the correct formula for the ionic compound?

Question

Which is the correct formula for the ionic compound formed by the transfer of electrons from Potassium to Oxygen?

Would it be:

A. KO

B. K2O

C.KO2

K2O2

Thanks for your help!

Answer 1

This isn't a terribly well worded question.  Because there are three correct answers.

It's possible to have K2O, KO2, and K2O2.

K2O = potassium oxide

K2O2 = potassium peroxide

KO2 = potassium superoxide

All of these are legitimate compounds of potassium and oxygen, and all can be produced when oxygen combines with potassium metal.

In each one potassium has an oxidation number of +1.  In the oxide, oxygen is -2, in the peroxide, each oxygen has an oxidation number of -1, and in the superoxide, each oxygen has an oxidation number of -1/2.

Answer 2

B  

Answer 3

B. K2O

Potassium(K) has a +1 charge, oxygen(O) has a -2 charge so you need 2 potassiums to get a total of +2 charge to cancel out the -2 charge of Oxygen.

Answer 4

K is 1+ charge,

O is 2- charge

Hence K2O, since the 2+ charges will balance out the 2- charge.