# What is the Lewis structure of calcium carbide?

$C {a}^{2 +} {\left[: C \equiv C :\right]}^{2 -}$
Around each carbon atom there are 5 valence electrons: 3 from the double bond, and 2 in a lone pair. Given the 2 inner shell electrons, this gives 7 electrons per carbon nucleus. Since, for carbon, $Z = 6$, each, carbon bears a formal negative charge, and thus there is a formal $2 -$ charge on the carbide ion (I was about to say the acetylide ion, but this is ""^(-)C-=C-H).