Is carbon a diatomic element?
Carbon is not a diatomic element. Diatomic elements are those where two atoms of the element can join to form a single molecule.
The diatomic elements are:
Bromine Iodine Fluorine Chlorine Oxygen Hydrogen Nitrogen
I like the acronym: Br I F Cl O H N (pronounced brifclone - the H is silent!) to help to remember these elements.