Period 
name (symbol) 
subshell electron configuration 
condensed electron configuration 
Period 1 (tutorial) 
hydrogen (H) 
1s^{1} 

helium (He) 
1s^{2} 

Period 2 (tutorial) 
lithium (Li) 
1s^{2} 2s^{1} 
[He] 2s^{1} 
beryllium (Be) 
1s^{2} 2s^{2} 
[He] 2s^{2} 
boron (B) 
1s^{2} 2s^{2} 2p^{1} 
[He] 2s^{2} 2p^{1} 
carbon (C) 
1s^{2} 2s^{2} 2p^{2} 
[He] 2s^{2} 2p^{2} 
nitrogen (N) 
1s^{2} 2s^{2} 2p^{3} 
[He] 2s^{2} 2p^{3} 
oxygen (O) 
1s^{2} 2s^{2} 2p^{4} 
[He] 2s^{2} 2p^{4} 
fluorine (F) 
1s^{2} 2s^{2} 2p^{5} 
[He] 2s^{2} 2p^{5} 
neon (Ne) 
1s^{2} 2s^{2} 2p^{6} 
[He] 2s^{2} 2p^{6} 
Period 3 (tutorial) 
sodium (Na) 
1s^{2} 2s^{2} 2p^{6} 3s^{1} 
[Ne] 3s^{1} 
magnesium (Mg) 
1s^{2} 2s^{2} 2p^{6} 3s^{2} 
[Ne] 3s^{2} 
aluminium (Al) 
1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{1} 
[Ne] 3s^{2} 3p^{1} 
silicon (Si) 
1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{2} 
[Ne] 3s^{2} 3p^{2} 
phosphorus (P) 
1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{3} 
[Ne] 3s^{2} 3p^{3} 
sulfur (S) 
1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{4} 
[Ne] 3s^{2} 3p^{4} 
chlorine (Cl) 
1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{5} 
[Ne] 3s^{2} 3p^{5} 
argon (Ar) 
1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{6} 
[Ne] 3s^{2} 3p^{6} 
Period 4 
potassium (K) 
1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{6} 4s^{1} 
[Ar] 4s^{1} 
calcium (Ca) 
1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{6} 4s^{2} 
[Ar] 4s^{2} 
scandium (Sc) 
1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{6} 3d^{1} 4s^{2} 
[Ar] 3d^{1} 4s^{2} 
titanium (Ti) 
1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{6} 3d^{2} 4s^{2} 
[Ar] 3d^{2} 4s^{2} 
vanadium (V) 
1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{6} 3d^{3} 4s^{2} 
[Ar] 3d^{3} 4s^{2} 
chromium (Cr) 
1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{6} 3d^{5} 4s^{1} 
[Ar] 3d^{5} 4s^{1} 
manganese (Mn) 
1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{6} 3d^{5} 4s^{2} 
[Ar] 3d^{5} 4s^{2} 
iron (Fe) 
1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{6} 3d^{6} 4s^{2} 
[Ar] 3d^{6} 4s^{2} 
cobalt (Co) 
1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{6} 3d^{7} 4s^{2} 
[Ar] 3d^{7} 4s^{2} 
nickel (Ni) 
1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{6} 3d^{8} 4s^{2} 
[Ar] 3d^{8} 4s^{2} 
copper (Cu) 
1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{6} 3d^{10} 4s^{1} 
[Ar] 3d^{10} 4s^{1} 
zinc (Zn) 
1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{6} 3d^{10} 4s^{2} 
[Ar] 3d^{10} 4s^{2} 
gallium (Ga) 
1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{6} 3d^{10} 4s^{2} 4p^{1} 
[Ar] 3d^{10} 4s^{2} 4p^{1} 
germanium (Ge) 
1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{6} 3d^{10} 4s^{2} 4p^{2} 
[Ar] 3d^{10} 4s^{2} 4p^{2} 
arsenic (As) 
1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{6} 3d^{10} 4s^{2} 4p^{3} 
[Ar] 3d^{10} 4s^{2} 4p^{3} 
selenium (Se) 
1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{6} 3d^{10} 4s^{2} 4p^{4} 
[Ar] 3d^{10} 4s^{2} 4p^{4} 
bromine (Br) 
1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{6} 3d^{10} 4s^{2} 4p^{5} 
[Ar] 3d^{10} 4s^{2} 4p^{5} 
krypton (Kr) 
1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{6} 3d^{10} 4s^{2} 4p^{6} 
[Ar] 3d^{10} 4s^{2} 4p^{6} 