Question

What is the name of the ionic compound CaO?

Answer 1

Calcium oxide
(common name: quicklime)

Explanation:

Calcium `Ca` is a metal, and is the compound's first name .
Compounds with oxygen `O` are called oxides. "-ide" is always a last name .

Since only `CaO` exists (one-to-one), no further specification is needed
(compare `CO` carbon monoxide and `CO_2` carbon dioxide)