What is the full electron configuration of the selenide ion?

• A. 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁴
• B. 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶
• C. 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁴ 5s²
• D. 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁸ 4p⁴ 5s² 5p²

Answer: (B)

Verified step by step guidance

1. Identify the neutral atom: Selenium (Se) is the neutral atom for the selenide ion. Its atomic number is 34, which means it has 34 electrons in its neutral state.
2. Write the electron configuration for the neutral selenium atom: The electron configuration for selenium is 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁴.
3. Determine the charge of the selenide ion: The selenide ion (Se^2-) has gained 2 additional electrons compared to the neutral selenium atom.
4. Add the extra electrons to the electron configuration: Since the selenide ion has 2 extra electrons, add these to the next available subshell, which is the 4p subshell. This changes the 4p⁴ to 4p⁶.
5. Write the full electron configuration for the selenide ion: The electron configuration for the selenide ion is 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶.