Which of the following is the correct electron configuration for the Be^{2+} ion?

• A. 1s^2
• B. 1s^0
• C. 1s^2 2s^2
• D. 1s^2 2s^0

Answer: (B)

Verified step by step guidance

1. Step 1: Identify the atomic number of beryllium (Be). Beryllium has an atomic number of 4, meaning it has 4 electrons in its neutral state.
2. Step 2: Write the electron configuration for neutral beryllium (Be). The electrons fill the orbitals in order of increasing energy: \$1s^2 2s^2$.
3. Step 3: Understand that the Be\(^{2+}\) ion means the beryllium atom has lost 2 electrons. Electrons are removed first from the highest energy level, which is the 2s orbital in this case.
4. Step 4: Remove 2 electrons from the 2s orbital of the neutral Be configuration. This leaves the electron configuration as \$1s^2 2s^0\(, which can be simplified to \)1s^2$ since the 2s orbital is empty.
5. Step 5: Conclude that the correct electron configuration for Be\(^{2+}\) is \$1s^2$, because the two electrons lost come from the 2s orbital, leaving only the filled 1s orbital.