Question

where 1s, 2s, and 2p are the occupied subshells, and the superscript "2" is the number of electrons in each of these subshells. Use the rules for determining electron configurations to write the electron configuration for Ca. Express your answer in complete form in order of orbital filling. For example, 1s22s2 should be entered as 1s^22s^2.

Answer 1

Answer: $1s^22s^22p^63s^23p^64s^2$

Explanation:

Electronic configuration represents the total number of electrons that a neutral element contains. We add all the superscripts to know the number of electrons in an atom.

The electrons are filled according to Afbau's rule in order of increasing energies where orbital with higher value of (n+l) has higher energy as compared to orbital having lower (n+l) value. Thus the electronic configuration for calcium with atomic number of 20 and hence containing 20 electrons is :

$Ca:20:1s^22s^22p^63s^23p^64s^2$