# 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.?

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 ${\Delta}_{\text{electronegativity}}$. Clearly, when we got a homonuclear bond, i.e. $H - H$, $C - C$, $N - N$ etc. ${\Delta}_{\text{electronegativity}} \equiv 0$. 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?