19
K
Potassium
39.09831
2881
#19

Potassium

alkali metal· Solid·39.09831 u

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.

Identity

Symbol
K
Atomic Number
19
Atomic Mass
39.09831 u
Category
alkali metal
Block
s-block
Period
4
Group
1
Appearance
silvery gray
Year Discovered
1807 CE
Discovered By
Humphry Davy
Named By
potash

Electrons

Configuration
[Ar] 4s1
Full Configuration
1s2 2s2 2p6 3s2 3p6 4s1
Shells
2, 8, 8, 1
Electronegativity
0.82
Electron Affinity
48.383
Oxidation States
+1
Ionization Energies
418.8, 3052, 4420, 5877, 7975 … +14 more

Physical Properties

Potassium
State at
Solid
Melting Point
336.7
Boiling Point
1032
Density
0.862
Molar Heat
29.6 J/(mol·K)
Crystal Structure
BCC
Magnetic Ordering
Paramagnetic

Mechanical

Atomic Radius
243 pm
Covalent Radius
203 pm
Van der Waals
275 pm
Metallic Radius
227 pm
Mohs Hardness
0.4
Brinell Hardness
0.363 MPa MPa
Bulk Modulus
3.1 GPa GPa
Shear Modulus
1.3 GPa GPa
Young's Modulus
3.53 GPa GPa

Thermal & Electrical

Thermal Conductivity
102.5 W/(m K) W/(m·K)
Electrical Conductivity
13.9 MS/m S/m
Specific Heat
757 J/(kg K) J/(g·K)
Heat of Vaporization
79.9 kJ/mol kJ/mol
Heat of Fusion
2.33 kJ/mol kJ/mol

Abundance

Universe
3 ppm
Sun
4 ppm
Meteorite
800 ppm
Earth's Crust
862.0 ppb
Ocean
392 ppm
Human Body
2000 ppm