## Chemistry: Principles and Practice (3rd Edition)

(a) nitrogen monoxide; molecular compound This compound is molecular because a compound made of two nonmetals are usually molecular because the electrons are shared between the two atoms. With molecular compounds, we write the name of the first element (nitrogen, N) and add a prefix denoting the number of atoms only if the number of atoms of the cation is greater than one. We then add the name of the anion (oxygen, O) with the prefix $mono-$ denoting that there is only one oxygen atom in this compound. We also change the ending of the anion to $-ide$. (b) yttrium sulfate; ionic compound This compound is ionic because it involves a metal bonded to a nonmetal; in these types of compounds, the electrons are transferred from one atom to another and are not shared. With ionic compounds, we keep the name of the cation (yttrium, Y) as-is. For the oxoanion (sulfate, SO$_4$), we also keep the name as-is. (c) sodium oxide; ionic compound This compound is ionic because it involves a metal bonded to a nonmetal; in these types of compounds, the electrons are transferred from one atom to another and are not shared. With ionic compounds, we keep the name of the cation (sodium, Na) as-is. For the anion (oxygen, O), we change the ending to $-ide$. (d) nitrogen tribromide; molecular compound This compound is molecular because a compound made of two nonmetals are usually molecular because the electrons are shared between the two atoms. With molecular compounds, we write the name of the first element (nitrogen, N) and add a prefix denoting the number of atoms only if the number of atoms of the cation is greater than one. We then add the name of the anion (bromine) with the prefix $tri-$ to denote that there are three bromine atoms in this compound. We also change the ending of the anion to $-ide$.