Question

What is the ground-state electron configuration for the element cobalt (z = 27)?

Answer 1

Cobalt is a Transition Element and it has a partially filled d-orbital. As given it has atomic number 27. In neutral state Cobalt has 27 electrons. These electrons are filled in following order,

                               1s², 2s², 2p⁶, 3s², 3p⁶, 4s², 3d⁷

Or it can also be written as,

                                              [Ar] 4s², 3d⁷

Where; [Ar] is Argon with electronic configuration 1s², 2s², 2p⁶, 3s², 3p⁶.