Question

How many lone pairs are present on carbon?

pc

How many lone pairs of electrons (if any) are present on the carbon with negative formal charge?

Answer 1

There is the ONE lone pair on the carbanion....

Explanation:

`H_3C-CH_2CH_2-CH_2^(-)`

There are 7 electron around the carbanion carbon.....3 electrons from the shared covalent bonds of `C-H` and `C-C`, and TWO electrons based on the carbon, and two inner core electrons (formally the `1s^2` set).

Because the ipso carbon claims 7 electrons, `2` from the lone pair, 2 from the `C-H` bonds, `1` from the `C-C` bond, and `2` inner core, the formal charge of carbon here is `-1`....(the nucular charge of carbon is of course +6, i.e. `Z=6`, and `6-7=-1`)...

Note that this is not a mere formalism: butyl-lithium contains the species as a polar organometallic molecule, and is widely used in organic chemistry, and represents this formalism.