How do you calculate chemical bond character based on the difference in electronegativity?

Question

I'm doing a WS for my HS chem class and it doesn't make sense.

but how do you "look up the electronegativity of each of the atoms on either side of the bond and subtract."???

Answer 1

Electronegativity measures how tightly an atom holds on to its electrons compared to other atoms. A high en means it holds on very strongly.

First you have to know how the molecule is bonded. Then, look up the electronegativity of each of the atoms on either side of the bond and subtract.

If the difference is 0 the bond is nonpolar covalent (neither atom is pulling on the electron more strongly)

If the difference is small ( I use less than 1.67 - check with your professor) then the bond is polar covalent. This means the electrons will be pulled slightly closer to the atom that has the higher electronegativity. The side with the higher en becomes slightly negative, the side with the smaller en becomes slightly positive.

If the difference is fairly large (I use more than 1.67) then the bond is ionic. The atom with the highter en gains possession of the electron and the atom with the lower en loses possession of the electron. True ions are formed.

Answer 2

There should be an electronegativity table in every general chemistry textbook; if not, look on a site like webelements.com to find standard electronegativity tables.

Answer 3

Could you explain your choice of vocabulary please?