What is the chemical formula for chromium(II) bromide?
The correct answer and explanation is:
The chemical formula for chromium(II) bromide is CrBr₂.
Chromium(II) refers to the oxidation state of chromium in this compound, which is +2. Bromide, the anion, has a charge of -1. To achieve electrical neutrality in the compound, two bromide ions are needed to balance the +2 charge of one chromium ion. This results in the formula CrBr₂, where chromium has a +2 charge and each bromide ion has a -1 charge. The overall charge of the compound is neutral, meaning the positive and negative charges balance out.
Chromium, a transition metal, can form multiple oxidation states, including +2, +3, and +6. In chromium(II) bromide, chromium is in the +2 oxidation state, which means it has lost two electrons. Chromium(II) compounds are generally less stable than chromium(III) compounds, and the Cr²⁺ ion is more easily oxidized to Cr³⁺.
The bromide ion is a halide, and halides typically form ionic bonds with metal cations. Bromide is a relatively large ion compared to other halides like chloride or fluoride, and it has a relatively low electronegativity, which is why it easily forms ionic compounds with metals like chromium.
In summary, the formula CrBr₂ reflects the need for two bromide ions to balance the +2 charge of chromium, forming a stable ionic compound. This formula is consistent with the rules of ionic bonding and the typical behavior of transition metal halides.