Answer
(a) manganese (II) sulfide
(b) vanadium (II) nitride
(c) chromium (III) sulfate
(d) cobalt (II) nitrate
(e) iron (III) oxide
Work Step by Step
Transition metal elements often have several oxidation numbers. To specify which oxidation number a particular transition metal atom has in a specific compound, Roman numerals inside parentheses are placed after the name of the transition metal. Then, we add the name of the anion, changing its ending to $-ide$.
(a) Mn stands for manganese; S stands for sulfur. We look first at the charge on the anion. Sulfur has a charge of $2-$. If manganese and sulfur have a one-to-one relationship, that means that manganese must have a charge of $2+$ to balance out the charge on sulfur. Therefore, the name of this compound is manganese (II) sulfide.
(b) V stands for vanadium; N stands for nitrogen. We look first at the charge on the anion. Nitrogen has a charge of $3-$. If vanadium and nitrogen have a three-to-two relationship, that means that vanadium must have a charge of $2+$ ($+2 x 3 = +6$) to balance out the charge on nitrogen ($-3 x 2 = -6$). Therefore, the name of this compound is vanadium (II) nitride.
(c) Cr stands for chromium; $SO_4$ stands for the oxoanion sulfate. We look first at the charge on the anion. Sulfate has a charge of $2-$. If chromium and sulfate have a two-to-three relationship, that means that chromium must have a charge of $3+$ ($+3 x 2 = +6$) to balance out the charge on sulfate ($-2 x 3 = -6$). Therefore, the name of this compound is chromium (III) sulfate.
(d) Co stands for cobalt; $NO_3$ stands for the oxoanion nitrate. We look first at the charge on the anion. Nitrate has a charge of $1-$. If cobalt and nitrate have a one-to-two relationship, that means that cobalt must have a charge of $2+$ ($+2 x 1 = +2$) to balance out the charge on nitrate ($-1 x 2 = -2$). Therefore, the name of this compound is cobalt (II) nitrate.
(e) Fe stands for iron; O stands for oxygen. We look first at the charge on the anion. oxygen has a charge of $2-$. If iron and oxygen have a two-to-three relationship, that means that iron must have a charge of $3+$ ($+3 x 2 = +6$) to balance out the charge on oxygen ($-2 x 3 = -6$). Therefore, the name of this compound is iron (III) oxide.
