What is the ground-state electron configuration of Co?

1 Answer
Apr 16, 2015

Cobalt has an atomic number of 27, which means that its atoms have 27 protons in their nuclei. In a neutral cobalt atom, there is also 27 electrons. The ground state electron configuration of cobalt is #"[Ar]3d"^7"4s"^2#. This noble gas notation means that cobalt has the electron configuration of argon plus the #"3d"^7"4s"^2# electrons. Argon has an atomic number of 18, and a neutral atom has 18 electrons. Add the 18 electrons from argon plus the 9 additional electrons for cobalt, and we get a total of 27 electrons, which is expected for cobalt.