Question

1. which list shows the first 7 sublevels that fill with electrons? * 4 points

a. 1s, 2s, 2p, 3s, 3p, 4s, 3d
b. 1s, 2s, 2p, 3s, 3p, 3d, 4s
c. 1s, 2s, 3s, 3p, 3d, 4s, 4p
d. 1s, 2p, 2d, 3s, 3p, 4s, 4p

Explanation:

Electrons fill sub - levels according to the Aufbau principle. The order of filling is 1s, 2s, 2p, 3s, 3p, 4s, 3d. This is because the 4s sub - level has a lower energy than the 3d sub - level for the first few elements.

Answer:

A. 1s, 2s, 2p, 3s, 3p, 4s, 3d