Which of the following correctly represents the electron affinity of bromine?

• A. Br(g) + e^- → Br^-(g)
• B. Br_2(g) + 2e^- → 2Br^-(g)
• C. Br(g) → Br^+(g) + e^-
• D. Br^-(g) → Br(g) + e^-

Answer: (A)

Verified step by step guidance

1. Understand that electron affinity refers to the energy change when a neutral atom in the gas phase gains an electron to form a negative ion.
2. Identify that the species involved must be a neutral atom (not a molecule or ion) in the gaseous state gaining an electron.
3. Write the general electron affinity reaction as: \(\text{X}(g) + e^- \rightarrow \text{X}^-(g)\), where X is a neutral atom.
4. Check each given reaction to see which one matches this pattern: a neutral bromine atom (Br) in the gas phase gaining one electron to form Br⁻(g).
5. Confirm that the correct representation is \(\mathrm{Br}(g) + e^- \rightarrow \mathrm{Br}^-(g)\), as it shows a neutral bromine atom gaining an electron to form the bromide ion.