Question

which of the following is the electron configuration for beryllium (be)? 1s²2s¹ 1s²2s² 1s²2s²2p² 1s²

Explanation:

Beryllium has an atomic number of 4, which means it has 4 electrons. Electrons fill orbitals in the order of increasing energy. The 1s orbital can hold 2 electrons and the 2s orbital can hold 2 electrons. So the electron - configuration for beryllium is $1s^{2}2s^{2}$.

Answer:

$1s^{2}2s^{2}$