Question

How do you use electronegativity values and the chemical formula of a substance to tell if the substance is nonpolar covalent, polar covalent, coordinate covalent, or ionic.?

Answer 1

You use these differences VERY selectively, and sometimes arbitrarily...

Explanation:

I myself find these tables a bit mickey mouse, inasmuch FIRST you have to have Tables of electronegativity in order to make the assessment of `Delta_"electronegativity"`. Clearly, when we got a homonuclear bond, i.e. `H-H`, `C-C`, `N-N` etc. `Delta_"electronegativity"-=0`. Most of the time, when presented with a compound, we can make a pretty good prediction as to whether it is covalent or ionic just by consideration of the constituent atoms: are they metal and non-metal; are they non-metal and non-metal?

An equally important distinction to make is whether the substance is molecular or NON-MOLECULAR. Non-molecular materials, e.g. carbon, salts, silica, have INTRINSICALLY HIGH melting and boiling points in comparison to molecular materials.