Be electron affinity around what value?

Be electron affinity around what value?

• A. 0; It has a completely filled 2s subshell.
• B. 50 kJ/mol
• C. -60 kJ/mol
• D. 100 kJ/mol

Answer: (A)

Electron affinity is the energy change when a neutral atom gains an electron. Beryllium has a completely filled 2s subshell in its ground state, so adding another electron would have to go into a higher-energy orbital and wouldn’t be stabilized by the existing structure. Because there’s no favorable stabilization from gaining that electron, little to no energy is released, making the value essentially zero. That’s why it’s described as around 0 kJ/mol. The other numbers would imply a significant energy change, which isn’t characteristic of Be’s closed-shell configuration.

Electron affinity is the energy change when a neutral atom gains an electron. Beryllium has a completely filled 2s subshell in its ground state, so adding another electron would have to go into a higher-energy orbital and wouldn’t be stabilized by the existing structure. Because there’s no favorable stabilization from gaining that electron, little to no energy is released, making the value essentially zero. That’s why it’s described as around 0 kJ/mol. The other numbers would imply a significant energy change, which isn’t characteristic of Be’s closed-shell configuration.