Question

The electronegativity difference between all hydrocarbons is so small that we expect these molecules to be what?

Answer 1

Electronegativity is an ATOMIC property, NOT a molecular property....

Explanation:

Hydrocarbons consist of `C-C` and `C-H` bonds.....Because the electronegativities of these elements are substantially the same, the `C-H`, and more so the `C-C` bond have only a trifling degree of polarity, i.e. charge separation. Smaller hydrocarbons are thus expected to be fairly volatile as there is little intermolecular interaction. As the hydrocarbyl chain grows larger, non-polar interactions between the chains becomes more significant, and boiling points become elevated.

For alcohols and amines, where the inclusion of the heteroatom introduces an atom that is substantially more electronegative than hydrogen, hydrogen bonding can operate to some extent with the result that the normal boiling points of methanol, ethanol, and methylamine are much greater than that of methane or ethane.......

`"methane, b.p."` `-164.0` `""^@C`

`"ethane, b.p."` `-89.0` `""^@C`

`"methylamine, b.p."` `-6.0` `""^@C`

`"ethylamine, b.p."` `16.0` `""^@C`

`"ethanol, b.p."` `78.0` `""^@C`

`"methanol, b.p."` `64.7` `""^@C`

`"ethanol, b.p."` `78.0` `""^@C`

The solvents with the higher normal boiling points also display substantial water solubilities. Why should this be so?