Name the following chemical compound: Zn(NO2)2. A. zinc(I) nitrite B. zinc(II) nitrite C. zinc(I) nitrate D. zinc(II) nitrate
The Correct Answer and Explanation is:
The correct answer is B. zinc(II) nitrite.
Explanation:
To name the compound Zn(NO2)2, we need to follow the rules for naming ionic compounds, specifically metal cations combined with polyatomic anions.
- Identify the metal and its charge:
The metal in the compound is zinc (Zn). Zinc is a transition metal, and it typically forms a +2 ion in its ionic compounds. This is because zinc has a consistent oxidation state of +2 in most of its compounds, making it zinc(II). - Identify the anion:
The anion in this compound is the nitrite ion, which is written as NO2-. The nitrite ion consists of a nitrogen atom bonded to two oxygen atoms and carries a single negative charge. It is different from the nitrate ion (NO3-), which has three oxygen atoms. - Combine the cation and anion:
The compound consists of one zinc ion (Zn²⁺) and two nitrite ions (NO2⁻). The subscript “2” indicates that two nitrite ions are required to balance the charge of the zinc ion. The overall formula is electrically neutral because the two negative charges from the nitrite ions balance the two positive charges from the zinc ion. - Naming convention:
- Zinc(II) indicates that the zinc ion has a +2 charge.
- Nitrite refers to the NO2⁻ ion.
Therefore, the name of Zn(NO2)2 is zinc(II) nitrite, which is option B.
Why other options are incorrect:
- A. zinc(I) nitrite: Zinc rarely forms a +1 charge in its compounds. It is more stable in the +2 oxidation state.
- C. zinc(I) nitrate: Nitrate (NO3-) is not present in this compound, and zinc does not typically form a +1 ion.
- D. zinc(II) nitrate: The anion in this compound is nitrite, not nitrate, making this name incorrect.
