Question

which of the following orbital diagrams is incorrect?

Explanation:

Step1: Recall Hund's rule

Electrons fill degenerate orbitals singly first with parallel spins before pairing up.

Step2: Analyze each option

In the second option, the 2s orbital has only one electron while the 2p orbitals are starting to be filled. According to the Aufbau principle, the 2s orbital should be completely filled (with 2 electrons) before filling the 2p orbitals.

Answer:

The second option (with 1s filled, 2s with one - electron and 2p orbitals starting to be filled) is incorrect.