Electronegativity and Chemical Bonds

By knowing whether the two elements in a bond are metal or nonmetal you can predict the bond type.

As you can see if one element is a metal and one is a nonmetal it will usually form an ionic bond.

As you can see if one element is a nonmetal and the other is a nonmetal it will usually form a covalent bond.

The pink diagonal line you see is called the stair-step.

The purple left of the stair-step are metals (with the exception of hydrogen)

The green right of the stair-step are nonmetals and included hydrogen

The pink colored elements that make up the stair-step are metalloids or semi-metals

Don't worry about the value. We want the absolute value (always positive) of the difference.