Question

13 multiple choice 5 points what is the last orbital filled for k? 2s 3s 4s 2p

Explanation:

Potassium (K) has an atomic number of 19. Its electron configuration is \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{1}\). According to the Aufbau principle, electrons fill orbitals in order of increasing energy. The \(4s\) orbital has lower energy than the \(3d\) orbital (for elements like K). So the last orbital filled is the \(4s\) orbital.

Answer:

4s