19  Potassium

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

+--------------------+
| 19     _  __       |
|       | |/ /       |
|       | ' /        |
|       | . \        |
|       |_|\_\       |
|                    |
|      Potassium     |
|      39.0983 u     |
+--------------------+

Electron Configuration: [Ar]4s1
Electronegativity:      0.82
Atomic Radius:          275 pm
Ionization Energy:      4.341 eV
Electron Affinity:      0.501 eV
Oxidation States:       1
Standard State:         Solid
Melting Point:          336.53 K
Boiling Point:          1032 K
Density:                0.89 g/cm3
Family:                 Alkali metal
Year Discovered:        1807
Number of Neutrons:     20
Number of Protons:      19
Number of Electrons:    19
Number of Valence:      1
Valency:                1
Group:                  1
Period:                 4
Shell:                  s-shell
Specific Heat:          0.757 J/g K
Radioactive:            0
Occurrence:             Natural
Source:                 Dying high-mass stars