What is the name of the compound with the formula Ba(NO2)2 ?
The Correct Answer and Explanation is:
Correct Answer: The name of the compound with the formula Ba(NO₂)₂ is barium nitrite.
Explanation:
This compound consists of two main parts: the metal barium (Ba) and the polyatomic ion nitrite (NO₂⁻). Understanding its name involves examining each component and the rules for naming ionic compounds.
Barium is a metal located in Group 2 of the periodic table. Elements in this group are known as alkaline earth metals and typically form +2 cations. Therefore, barium forms the Ba²⁺ ion. Since it has a fixed charge, it does not require a Roman numeral in its name.
Nitrite is a polyatomic ion composed of one nitrogen atom and two oxygen atoms, carrying a -1 charge. The formula NO₂⁻ distinguishes nitrite from nitrate (NO₃⁻), which contains one more oxygen atom. Despite their similar structures, the names differ to reflect the oxygen content: nitrite has fewer oxygen atoms than nitrate.
To form a neutral ionic compound, two nitrite ions, each with a -1 charge, combine with one barium ion, which has a +2 charge. This results in the formula Ba(NO₂)₂, indicating one barium ion and two nitrite ions. The subscript “2” outside the parentheses around NO₂ shows that two of these ions are needed for charge balance.
Naming follows standard conventions for ionic compounds:
- Start with the name of the cation: barium.
- Follow with the name of the anion: nitrite (not nitride, which would indicate a different anion entirely).
No prefixes like “di-” or “tri-” are used because this is an ionic compound, and such prefixes apply only to covalent compounds.
Therefore, barium nitrite is the correct and complete name for Ba(NO₂)₂.
