Question

What is the electron configuration of the element with 27 protons?

Answer 1

The electronic configuration of cobalt is :1s2 2s2 2p6 3s2 3p6 3d7 4s2 

Answer 2

Answer: $Co:27:1s^22s^22p^63s^23p^64s^23d^7$

Explanation: A neutral element with 27 protons will have 27 electrons and thus has a atomic number of 27. The element with atomic number 27 is cobalt and the nearest noble gas is argon with 18 electrons.

The electrons are filled according to Afbau's rule in order of increasing energies.

$Co:27:1s^22s^22p^63s^23p^64s^23d^7$

The electronic configuration in terms of noble gs configuration is:  

$Co:27:[Ar]4s^23d^7$