Electron configurations

The first twenty elements

  1 2 13 14 15 16 17 18
1
hydrogen
1		            
helium
2
2
lithium
2.1
beryllium
2.2
boron
2.3
carbon
2.4
nitrogen
2.5
oxygen
2.6
fluorine
2.7
neon
2.8
3
sodium
2.8.1
magnesium
2.8.2
aluminium
2.8.3
silicon
2.8.4
phosphorus
2.8.5
sulfur
2.8.6
chlorine
2.8.7
argon
2.8.8
4
potassium
2.8.8.1
calcium
2.8.8.2		            


The complete periodic table

  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
1 H                                 He
2 Li Be                     B C N O F Ne
3 Na Mg                     Al Si P S Cl Ar
4 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
5 Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe
6 Cs Ba * Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn
7 Fr Ra ** Rf Db Sg Bh Hs Mt Ds Rg Cn            
* La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu *
** Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr **


More advanced theories

See http://www.benjamin-mills.com/teaching/chemistry/electron-configurations/.