How do electronegativity values help determining the polarity of a bond?

Answer 1

Electronegativity is a measure of how well an atom in a molecule will attract electrons from a bond. The higher an atom's electronegativity, the better it is at attracting electrons from a bond and the more time the electrons will want to spend on that atom. To determine how polar a bond is, you need to look at the electronegativities of the two bonded atoms. The difference in electronegativity will indicate how polar the bond is: If you have a large electronegativity difference then one atom (the one with the higher electronegativity) will attract the electrons from the bond more, so the electrons will spend a disproportionate amount of time on that atom giving it a partial negative charge and the atom it's bonded to a partial positive charge. If you have a small electronegativity difference then neither atom will be able to draw the electrons away from the bond that well and so the bond will only be slightly polar or not polar at all if the electronegativities are the same.

Answer 2

Electronegativities vary for each element. It is the ability of an atom to attract a pair of electrons in a chemical bond. If two atoms have the same electronegativity, they will form a covalent bond. This only occurs for atoms of the same kind like a carbon- carbon bond. Quite often two atoms have very similar electronegativities such as carbon and hydrogen. These will form a covalent bond which is only very slightly polar. If two atoms are of quite different electronegativities, they will form a very polar covalent bond such as carbon and fluorine. Fluorine attracts the electron pair shared in the bond harder than carbon does so the fluorine side of the bond will be negative. It is still not hard enough to be called an ionic bond. Sodium has a low electronegativity so in a bond between sodium and fluorine, the fluorine will completely rob the sodium of its electron. They will attract each other because they have opposite charges. Because the sodium has lost an electron it will have a positive charge. Metals have low electronegativity values while non-metals have high values. This is why non-metals form bonds with themselves such as O2 while metals don't. The first table of electronegativities was drawn up by Linus Pauling in 1936.

Answer 3

A great difference of the electronegativities of two elements lead to a polar bond and inversely to a nonpolar bond. For example the diatomic molecule of hydrogen is not polar but the molecule of hydrogen chloride is polar. The most common scale of electronegativity is from Linus Pauling.