Question

Given the following pairs of elements, predict whether they will form a bond that is primarily ionic or covalent.  Be able to explain

Lithium and oxygen
Fluorine and Chlorine
Calcium and Sulfur

Answer 1

if there is a great difference in electromagnetic values, then the molecule will be primarily ionic. typically this is 0.3+

if there is a small difference in electromagnetic values, then the molecule will be primarily covalent. typically this is <0.3

you can find the differences by looking at a periodic table, using the given electromagnetic values, and using simple subtraction