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.
Read key information and facts about element Potassium
|Group in Periodic Table||1|
|Group Name||lithium family|
|Period in Periodic Table||4|
|Block in Periodic Table||s-block|
|Electronic Configuration||[Ar] 4s1|
|Melting Point||63.38 °C|
|Boiling Point||759 °C|
|Electronic Shell Structure||[2, 8, 8, 1]|
Periodic table is arranged by atomic number, number of protons in the nucleus which is same as number of electrons. The atomic number increases from left to right. Periodic table starts at top left ( Atomic number 1) and ends at bottom right (atomic number 118). Therefore you can directly look for atomic number 19 to find Potassium on periodic table.
Another way to read periodic table and locate an element is by using group number (column) and period number (row). To locate Potassium on periodic table look for cross section of group 1 and period 4 in the modern periodic table.
The element Potassium was discovered by Humphry Davy in year 1807 in United Kingdom . Potassium derived its name from New Latin potassa, 'potash' (kalium in Latin)
The table below shows the abundance of Potassium in Universe, Sun, Meteorites, Earth's Crust, Oceans and Human Body.
|Ppb by weight (1ppb =10^-7 %)|
|Abundance in Universe||3e-06|
|Abundance in Sun||4e-06|
|Abundance in Meteorites||0.0007|
|Abundance in Earth's Crust||0.015|
|Abundance in Oceans||0.00042|
|Abundance in Humans||0.002|
The solid state structure of Potassium is Body Centered Cubic.
The Crystal structure can be described in terms of its unit Cell. The unit Cells repeats itself in three dimensional space to form the structure.
The unit cell is represented in terms of its lattice parameters, which are the lengths of the cell edges Lattice Constants (a, b and c)
and the angles between them Lattice Angles (alpha, beta and gamma).
The positions of the atoms inside the unit cell are described by the set of atomic positions ( xi, yi, zi) measured from a reference lattice point.
The symmetry properties of the crystal are described by the concept of space groups. All possible symmetric arrangements of particles in three-dimensional space are described by the 230 space groups (219 distinct types, or 230 if chiral copies are considered distinct.
|Space Group Name||Im_ 3m|
|Space Group Number||229|
|Crystal Structure||Body Centered Cubic|
Potassium atoms have 19 electrons and the electronic shell structure is [2, 8, 8, 1] with Atomic Term Symbol (Quantum Numbers) 2S1/2.
|Number of Electrons (with no charge)||19|
|Number of Protons||19|
|Number of Neutrons||20|
|Shell structure (Electrons per energy level)||[2, 8, 8, 1]|
|Electron Configuration||[Ar] 4s1|
|Atomic Term Symbol (Quantum Numbers)||2S1/2|
Shell Structure of Potassium - Electrons per energy level
The ground state electronic configuration of Neutral Potassium atom is [Ar] 4s1. The portion of Potassium configuration that is equivalent to the noble gas of the preceding period, is abbreviated as [Ar]. For atoms with many electrons, this notation can become lengthy and so an abbreviated notation is used.This is important as it is the Valence electrons 4s1, electrons in the outermost shell that determine the chemical properties of the element.
Complete ground state electronic configuration for the Potassium atom, Unabbreviated electronic configuration
1s2 2s2 2p6 3s2 3p6 4s1
Potassium atomic radius is 243 pm, while it's covalent radius is 196 pm.
243 pm (2.43 Å)
|Atomic Volume||45.6755841121 cm3|
|Covalent Radius||196 pm (1.96 Å)|
|Van der Waals Radius||275 pm|
|Neutron Cross Section||2.1 σa/barns|
The electron affinity of Potassium is 48.4 kJ/mol
Refer to table below for Ionization energies of Potassium
|Ionization energy number||Enthalpy - kJ/mol|
Refer to below table for Potassium Physical Properties
|Molar Volume||45.6755841121 cm3|
|Shear Modulus||1.3 GPa|
|Bulk Modulus||3.1 GPa|
|Mohs Hardness||0.4 MPa|
|Brinell Hardness||0.363 MPa|
Potassium is Conductor of electricity. Refer to table below for the Electrical properties of Potassium
|Electrical Conductivity||1.4×107 S/m|
|Resistivity||7×10-8 m Ω|
|Thermal Conductivity||100 W/(m K)|
|Mass Magnetic Susceptibility||6.7×10-9|
|Molar Magnetic Susceptibility||2.62×10-10|
|Volume Magnetic Susceptibility||5.74×10-6|
|Speed of Sound||2×103 m/s|
Refer to table below for Thermal properties of Potassium
|Melting Point||336.53 K (63.38 °C)|
|Boiling Point||1032 K (759 °C)|
|Critical Temperature||2223 K|
|Heat of Fusion||2.33 kJ/mol|
|Heat of Vaporization||76.9 kJ/mol|
|Heat of Combustion||-182 J/(kg K)|
Isotopes of rhodium. Naturally occurring Potassium has 2 stable isotope - 39K, 41K.
|Isotope||Isotope Mass||% Abundance||T half||Decay Mode|
|DOT Hazard Class||4.3|
|NFPA Fire Rating||3|
|NFPA Hazards||Water Reactive|
|NFPA Health Rating||3|
|NFPA Reactivity Rating||2|
|Autoignition Point||440 °C|
List of unique identifiers to search the element in various chemical registry databases
|CAS Number - Chemical Abstracts Service (CAS)||CAS7440-09-7|
|Alkali Metals||Alkaline Earth Metals|
|Transition Metals||Post-Transition Metals|