Question

Two carbon atoms held together in a double covalent bond share how many electron?

Answer 1

A `C=C` bond is composed of 4 electrons.

Explanation:

Consider ethylene, `H_2C=CH_2`. Each hydrogen atom has the one electron available for bonding. Each carbon atom has 4 electrons available for bonding. (The remaining electrons `C, Z=6` are inner core, and are not presumed to be involved in bonding.)

So in a olefin bond `C: + :C` gives the `C=C` junction.