Potassium

19
K
Group
1
Period
4
Block
s
Protons
Electrons
Neutrons
19
19
20
General Properties
Atomic Number
19
Atomic Weight
39.0983
Mass Number
39
Category
Alkali metals
Color
Silver
Radioactive
No
From the English word, potash - pot ashes; Latin kalium, Arab qali, alkali
Crystal Structure
Body Centered Cubic
History
Potassium's symbol K comes from 'kalium' the name of the element in Germany and Scandinavia.

Potassium metal was first isolated in 1807 by Sir Humphry Davy, who derived it from caustic potash by the use of electrolysis of the molten salt with the newly discovered voltaic pile.

Potassium was the first metal that was isolated by electrolysis.
Electrons per shell
2, 8, 8, 1
Electron Configuration
[Ar] 4s1
K
People whose diets are low in potassium can suffer from hypokalemia
Physical Properties
Phase
Solid
Density
0.862 g/cm3
Melting Point
336.53 K | 63.38 °C | 146.08 °F
Boiling Point
1032.15 K | 759 °C | 1398.2 °F
Heat of Fusion
2.33 kJ/mol
Heat of Vaporization
76.9 kJ/mol
Specific Heat Capacity
0.757 J/g·K
Abundance in Earth's crust
1.5%
Abundance in Universe
0.0003%
Potassium
Image Credits: Images-of-elements
Potassium pearls under paraffin oil
CAS Number
7440-09-7
PubChem CID Number
5462222
Atomic Properties
Atomic Radius
227 pm
Covalent Radius
203 pm
Electronegativity
0.82 (Pauling scale)
Ionization Potential
4.3407 eV
Atomic Volume
45.46 cm3/mol
Thermal Conductivity
1.024 W/cm·K
Oxidation States
-1, 1
Applications
The greatest demand for potash has been in its use for fertilizers.

Potassium is an essential constituent for plant growth and is found in most soils.

Potassium nitrate is the main explosive ingredient in gunpowder.

Potassium hydroxide is used in the manufacture of soft soaps and as an electrolyte in alkaline batteries.
Potassium must be handled with great care with full skin and eye protection
Isotopes
Stable Isotopes
39K, 41K
Unstable Isotopes
32K, 33K, 34K, 35K, 36K, 37K, 38K, 40K, 42K, 43K, 44K, 45K, 46K, 47K, 48K, 49K, 50K, 51K, 52K, 53K, 54K, 55K