Periodic System for Chemists
Table
19
39.10

K

Potassium

Identification

CAS Number: 7440-09-7
Discovery Year: 1807
Discoverer: Sir Humphrey Davy
Discovery Location: England

Properties

Atomic Mass: 39.0983 →Density: 0.89 g/cm³ →
Crust Abundance: 20900 mg/kg
Crystal Structure: BCC

Atomic Dimensions

Atomic Radius: 220 pm →
Atomic Radius (Rahm): 234 pm
Covalent Radius: 202.99999999999997 pm →
Van der Waals Radius: 275 pm
Metallic Radius: 203 pm
Atomic Volume: 45.3 cm³/mol
Lattice Constant: 5.23 Å

Thermodynamics

Melting Point: 336.8 K →Boiling Point: 1047 K →Specific Heat: 0.753 J/(g·K) →Thermal Conductivity: 79 W/(m·K) →Heat of Fusion: 102.5 kJ/mol →Heat of Vaporization: 2.33 kJ/mol →
Heat of Formation: 89 kJ/mol

Electronic Structure

Electron Config: [Ar] 4s
Block: s
Period: 4 →Group: 1 →Electronegativity: 0.82 →Electron Affinity: 0.50147 eV →
Oxidation States: +1

Abundance & Geochemistry

Crust Abundance: 20900 mg/kg
Sea Abundance: 399 mg/L
Geochemical Class: alkali metal
Goldschmidt Class: litophile

About

Potassium is a soft, silvery-white metal that is essential for life. It is commonly found in bananas and is used in fertilizers.

Isotopes

K-39 39 93.26%
K-41 41 6.73%
K-40 40 0.0117%