19 - Potassium alkali metal
Discovered by Humphry Davy in 1807
Potassium is a chemical element with symbol K (derived from Neo-Latin, kalium) and atomic number 19. It was first isolated from potash, the ashes of plants, from which its name is derived. In the Periodic table, potassium is one of seven elements in column (group) 1 (alkali metals):they all have a single valence electron in their outer electron shell, which they readily give up to create an atom with a positive charge - a cation, and combine with anions to form salts.
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 Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn Fr Ra Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr Rf Db Sg Bh Hs Mt Ds Rg Cn Nh Fl Mc Lv Ts Og
57-71 La-Lu Lanthanides
89-103 Ac-Lr Actinides
| Shell | Electrons | Orbitals |
|---|---|---|
| 1 | 2 | 2 in 1s |
| 2 | 8 | 2 in 2s + 6 in 2p |
| 3 | 8 | 2 in 3s + 6 in 3p |
| 4 | 1 | 1 in 4s |
silvery gray Appearance
39.1 u Atomic Mass
2.2 Å Atomic Radius
1.03k K Boiling Point
1 Group
1 Common Oxidation States
2.03 Å Covalent Radius
0.862 g/cm³ Density
48.4 kJ/mol Electron Affinity
1s2 2s2 2p6 3s2 3p6 4s1 Electron Configuration
[Ar] 4s1 Electron Configuration (semantic)
0.82 Electronegativity
19 Electrons
4.34 eV First Ionization Energy
1 ICSD Oxidation States
418.8, 3052, 4420, 5877, 7975, 9590, 11343, 14944, 16963.7, 48610, 54490, 60730, 68950, 75900, 83080, 93400, 99710, 444880, 476063 kJ/mol Ionization Energies
337 K Melting Point
10 Mendeleev Number
29.6 J/(mol·K) Molar Heat
4 Number of Shells
1 Electron Valency
20 Neutrons
19 Atomic Number
10 Number of Isotopes
-1, 1 Oxidation States
4 Period
Solid Phase
19 Protons
2, 8, 8, 1 Electron Shell Occupations
0.757 J/(g K) Specific Heat