Potassium

Potassium (K)

Soft silvery metallic element belonging to group 1 of the periodic table (alkali metals). Occurs naturally in seawater and a many minerals. Highly reactive, chemically, it resembles sodium in its behavior and compounds. Discovered by Sir Humphry Davy in 1807.
Atomic Number19
Atomic Weight39.0983
Mass Number39
Group1
Period4
Blocks
Protons19 p+
Neutrons20 n0
Electrons19 e-
Kalium.jpg Animated Bohr Model Enhanced Bohr Model Bohr Model Orbital Diagram

Properties

Atomic Radius
220 pm
Atomic Volume
Covalent Radius
196 pm
Metallic Radius
203 pm
Ionic Radius
137 pm
Crystal Radius
151 pm
Van der Waals radius
275 pm
Density
0.89 g/cm³
Boiling Point
1,047 K
Melting Point
336.8 K
Electrons per shell2, 8, 8, 1
Electronegativity
0.82
Electrophilicity
0.7633848415986 eV/particle
Proton Affinity
Electron Affinity
0.50147 eV/particle
Ionization Potential
4.34066354 eV/particle
Heat of Vaporization
2.33 kJ/mol
Heat of Fusion
102.5 kJ/mol
Heat of Formation
Molar Heat Capacity
Specific Heat Capacity
0.757 J/(g⋅K)
Thermal Conductivity
Gas Basicity
Dipole Polarizability
289.7 a₀
C6 Dispersion Coefficient
3,923 a₀
Oxidation States-1, 1
Color
Silver
Crystal StructureBody Centered Cubic (BCC)
Lattice Constant
5.23 Å
Bulk Modulus
Electrical Resistivity
Electron Configuration[Ar] 4s1
Magnetic Ordering
Magnetic Susceptibility
PhaseSolid
Poisson Ratio
Shear Modulus
Young's Modulus
Allotropes
Alternate Names
Adiabatic Index
Appearance
Electric Conductivity
Critical Pressure
Critical Temperature
Curie Point
Electrical
Hardness
Magnetic Susceptibility
Magnetic
Neel Point
Neutron Cross Section
Neutron Mass Absorption
Gas Phase
Quantum Numbers
Refractive Index
Space Group
Speed of Sound
Superconducting Point
Thermal Expansion
Valence Electrons
Classification
CategoryAlkali metals, Alkali metals
CAS GroupIA
IUPAC GroupIA
Glawe Number10
Mendeleev Number3
Pettifor Number10
Geochemical Classalkali metal
Goldschmidt Classlitophile
Radioactivity
RadioactiveNo
Decay Mode
Half-Life
Lifetime
Abundance
Abundance in Earth's crust
20,900 mg/kg
Abundance in Oceans
399 mg/L
Abundance in Human Body
Abundance in Meteor
Abundance in Sun
Abundance in Universe0.0003%

Isotopes of Potassium

Stable Isotopes
39K 40K 41K
Unstable Isotopes
32K 33K 34K 35K 36K 37K 38K 42K 43K 44K 45K 46K 47K 48K 49K 50K 51K 52K 53K 54K 55K

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. From the English word, potash - pot ashes; Latin kalium, Arab qali, alkali

DiscoverersSir Humphrey Davy
Discovery LocationEngland
Discovery Year1807
Name OriginEnglish: pot ash; symbol from Latin: kalium, (alkali).
Potassium must be handled with great care with full skin and eye protection
People whose diets are low in potassium can suffer from hypokalemia

Uses

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. Used as potash in making glass & soap. Also as saltpeter, potassium nitrate (KNO3) to make explosives and to color fireworks in mauve. Formerly called kalium (K). Vital to function of nerve and muscle tissures.

Sources

Found in minerals like carnallite [(KMgCl3).6H2O] & sylvite (potassium chloride, KCL). Pure metal is produced by the reaction of hot potassium chloride and sodium vapors in a special retort.