The partial electron configuration of an atom with 14 electrons is shown.

1s22s2 2p63s2X

Which of the following does X represent?

a. 2d2

b. 3s2

c. 3p2

d. 4s2

Given:

Atomic number of an atom = 14

Partial electron configuration = 1s²2s²2p⁶3s²X

To determine:

The identity of X

Explanation:

Based on the Aufbau rule, the order in which the orbitals fill up based on energetic considerations is:

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

maximum # electrons in s orbital = 2, p = 6, d = 10 and so on

Since 3p would follow the 3s orbital, in this case we will have the full configuration as:

1s²2s²2p⁶3s²3p²

Ans c) X = 3p²