Question

Question #cf092

Answer 1

You can use arbitrary values of `ΔEN` to classify the bond type, but you can also use your knowledge of molecular geometry and structure to predict this as well.

Explanation:

In arbitrary units, the Pauling scale:

Nonpolar covalent bonds when, `ΔEN<0.5`
Polar covalent bonds when, `0.5 < ΔEN < 1.7`
Ionic bonds when, `ΔEN>1.7`

Of course, you need some sort of chart or table to do this (mainly the Pauling scale values), but if you do not have a chart with electronegativity values to compare, consider this:

If the compound is ionic (metal + nonmetal constituents) the bond formed will be ionic.

If the compound is molecular, the bond formed could be a polar covalent bond or a nonpolar covalent bond depending on "close" the bonded species are on the periodic table.

As expected then, for diatomics, the bond is formed is nonpolar covalent. Such as `F_2` or `O_2`.

But, the bond between two molecular species can sometimes be ionic, in the case of `BF_3` for example - so be careful. It's best to use elctronegativity values to calculate `ΔEN` when you can.

You can find elctronegavity values here:
http://www.ptable.com/#Property/Electronegativity