Question #52cc0

A covalent compound is formed when two or more atoms share electrons located in their outermost shells, i.e. valence electrons, to gain stability.

Covalent compounds are formed between elements that have relatively similar electronegativities, which implies that the bonding electrons each atom uses are shared in a relatively equal manner.

Nonmetals are the only elements capable of forming covalent compounds. With the exception of hydrogen, which only needs 2 electrons in its outermost shell in order to be stable (complete its duet), all other nonmetals that react to form covalent compounds do so in order to complete their octet.

So, the first rule you need to go by when trying to decide whether or not a compound is predominantly covalent is to chewck for metals.

Since nonmetals are the only ones capable of forming covalent compounds, any compound that contains a metal and a nonmetal will not be considered covalent.

In your case, cobalt (II) fluoride, #CoF_2#, magnesium oxide, #MgO#, and copper sulfide, #CuS#, all contain metals bonded to nonmetals.

The only covalent compound in your list is sulfur dibromide, #SBr_2#, which is formed when two bromine atoms covalently bond with a sulfur atom.