Question

why carbon forms compounds by sharing and not by the formation of ions

Answer 1

because if they had been formed by formation of ions then electron would have been increased or the proton could have been increased

Answer 2

Covalent bonding is the sharing of electrons between atoms. ... To form ionic bonds, Carbon molecules must either gain or lose 4 electrons. This is highly unfavorable; therefore, carbonmolecules share their 4 valenceelectrons through single, double, and triple bonds so that each atom can achieve noble gas configurations.