User:Himansh varshney

Electic atoms

3.4 - Electron Configurations of Atoms 3.4.3 - Electron Configuration for Atoms of the First 20 Elements

When the electrons are arranged in their lowest energy state, the atom is in the ground state. The following table summarizes the ground state electron configuration of the first 20 elements on the periodic table.

NB: the superscripts add up to the atomic number of the atom.

Name	Atomic Number	Electron Configuration Period 1 Hydrogen	1	1s1 Helium	2	1s2 Period 2 Lithium	3	1s2 2s1 Beryllium	4	1s2 2s2 Boron	5	1s2 2s22p1 Carbon	6	1s2 2s22p2 Nitrogen	7	1s2 2s22p3 Oxygen	8	1s2 2s22p4 Fluorine	9	1s2 2s22p5 Neon	10	1s2 2s22p6 Period 3 Sodium	11	1s2 2s22p63s1 Magnesium	12	1s2 2s22p63s2 Aluminum	13	1s2 2s22p63s23p1 Silicon 14

1s2 2s22p63s23p2 Phosphorus	15	1s2 2s22p63s23p3 Sulfur	16	1s2 2s22p63s23p4 Chlorine	17	1s2 2s22p63s23p5 Argon	18	1s2 2s22p63s23p6 Period 4 Potassium	19	1s2 2s22p63s23p64s1 Calcium	20	1s2 2s22p63s23p64s2