Potassium History
The element Potassium was discovered by H. Davy in year 1807 in United Kingdom. Potassium was first isolated by H. Davy in 1807. Potassium derived its name from New Latin potassa, 'potash' (kalium in Latin).
| Discovered By | H. Davy |
| Discovery Date | 1807 in United Kingdom |
| First Isolation | 1807 |
| Isolated by | H. Davy |
Davy discovered it by using electrolysis on potash.
Potassium Uses
Potassium is mainly used in compounds. It is mixed with chlorine to produce potassium chloride, which is used in fertilizers, pharmaceuticals, and saline drips. Potassium hydroxide is also used in soaps and cleaners, while Potassium carbonate is used in the manufacturing of glass.
Potassium Presence: Abundance in Nature and Around Us
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 %) | ppb by atoms (1ppb =10^-7 %) | |
|---|---|---|
| Abundance in Universe | 3000 | 100 |
| Abundance in Sun | 4000 | 100 |
| Abundance in Meteorites | 710000 | 370000 |
| Abundance in Earth's Crust | 15000000 | 7800000 |
| Abundance in Oceans | 416000 | 65800 |
| Abundance in Humans | 2000000 | 320000 |
Crystal Structure of Potassium
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.
Unit Cell Parameters
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)
| a | b | c |
|---|---|---|
| 532.8 pm | 532.8 pm | 532.8 pm |
and the angles between them Lattice Angles (alpha, beta and gamma).
| alpha | beta | gamma |
|---|---|---|
| π/2 | π/2 | π/2 |
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 |
| Number of atoms per unit cell | 2 |
The number of atoms per unit cell in a simple cubic, face-centered cubic and body-centred cubic are 1,4,2 respectively.
Potassium Atomic and Orbital Properties
Potassium atoms have 19 electrons and the electronic shell structure is [2, 8, 8, 1] with Atomic Term Symbol (Quantum Numbers) 2S1/2.
| Atomic Number | 19 |
| Number of Electrons (with no charge) | 19 |
| Number of Protons | 19 |
| Mass Number | 39 |
| Number of Neutrons | 20 |
| Shell structure (Electrons per energy level) | 2, 8, 8, 1 |
| Electron Configuration | [Ar] 4s1 |
| Valence Electrons | 4s1 |
| Valence (Valency) | 1 |
| Main Oxidation States | 1 |
| Oxidation States | -1, 1 |
| Atomic Term Symbol (Quantum Numbers) | 2S1/2 |
Ground State Electronic Configuration of Potassium - neutral Potassium atom
Abbreviated electronic configuration of Potassium
The ground state abbreviated 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.
Unabbreviated electronic configuration of neutral Potassium
Complete ground state electronic configuration for the Potassium atom, Unabbreviated electronic configuration
1s2 2s2 2p6 3s2 3p6 4s1
Electrons are filled in atomic orbitals as per the order determined by the Aufbau principle, Pauli Exclusion Principle and Hund’s Rule.
Atomic Structure of Potassium
Potassium atomic radius is 243 pm, while it's covalent radius is 196 pm.
| Atomic Radius Calculated | 243 pm(2.43 Å) |
| Atomic Radius Empirical | 220 pm (2.2 Å) |
| Atomic Volume | 45.68 cm3/mol |
| Covalent Radius | 196 pm (1.96 Å) |
| Van der Waals Radius | 275 pm |
| Neutron Cross Section | 2.1 |
| Neutron Mass Absorption | 0.0018 |
Spectral Lines of Potassium - Atomic Spectrum of Potassium
A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from an excess or deficiency of photons in a narrow frequency range, compared with the nearby frequencies. Spectral lines are often used to identify atoms and molecules.
Spectral lines are the result of interaction between a quantum system and a single photon. A spectral line may be observed either as an emission line or an absorption line.
Spectral lines are highly atom-specific, and can be used to identify the chemical composition of any medium. Several elements, including helium, thallium, and caesium, were discovered by spectroscopic means. They are widely used to determine the physical conditions of stars and other celestial bodies that cannot be analyzed by other means.
Emission spectrum of Potassium
Absorption spectrum of Potassium
Potassium Chemical Properties: Potassium Ionization Energies and electron affinity
The electron affinity of Potassium is 48.4 kJ/mol.
| Valence | 1 |
| Electronegativity | 0.82 |
| ElectronAffinity | 48.4 kJ/mol |
Ionization Energy of Potassium
Ionization energy is the amount of energy required to remove an electron from an atom or molecule.in chemistry, this energy is expresed in kilocalories per mole (kcal/mol) or kilojoules per mole (kJ/mol).
Refer to table below for Ionization energies of Potassium
| Ionization energy number | Enthalpy - kJ/mol |
|---|---|
| 1st | 418.8 |
| 2nd | 3052 |
| 3rd | 4420 |
| 4th | 5877 |
| 5th | 7975 |
| 6th | 9590 |
| 7th | 11343 |
| 8th | 14944 |
| 9th | 16963.7 |
| 10th | 48610 |
| 11th | 54490 |
| 12th | 60730 |
| 13th | 68950 |
| 14th | 75900 |
| 15th | 83080 |
| 16th | 93400 |
| 17th | 99710 |
| 18th | 444880 |
| 19th | 476063 |
Potassium Physical Properties
Refer to below table for Potassium Physical Properties
| Density | 0.856 g/cm3(when liquid at m.p density is $0.828 g/cm3) |
| Molar Volume | 45.68 cm3/mol |
Elastic Properties
| Young Modulus | - |
| Shear Modulus | 1.3 GPa |
| Bulk Modulus | 3.1 GPa |
| Poisson Ratio | - |
Hardness of Potassium - Tests to Measure of Hardness of Element
| Mohs Hardness | 0.4 MPa |
| Vickers Hardness | - |
| Brinell Hardness | 0.363 MPa |
Potassium Electrical Properties
Electrical resistivity measures element's electrical resistance or how strongly it resists electric current.The SI unit of electrical resistivity is the ohm-metre (Ω⋅m). While Electrical conductivity is the reciprocal of electrical resistivity. It represents a element's ability to conduct electric current. The SI unit of electrical conductivity is siemens per metre (S/m).
Potassium is a conductor of electricity. Refer to table below for the Electrical properties of Potassium
| Electrical conductors | Conductor |
| Electrical Conductivity | 14000000 S/m |
| Resistivity | 7e-8 m Ω |
| Superconducting Point | - |
Potassium Heat and Conduction Properties
| Thermal Conductivity | 100 W/(m K) |
| Thermal Expansion | - |
Potassium Magnetic Properties
| Magnetic Type | Paramagnetic |
| Curie Point | - |
| Mass Magnetic Susceptibility | 6.7e-9 m3/kg |
| Molar Magnetic Susceptibility | 2.62e-10 m3/mol |
| Volume Magnetic Susceptibility | 0.00000574 |
Optical Properties of Potassium
| Refractive Index | - |
Acoustic Properties of Potassium
| Speed of Sound | 2000 m/s |
Potassium Thermal Properties - Enthalpies and thermodynamics
Refer to table below for Thermal properties of Potassium
| Melting Point | 336.53 K(63.38 °C, 146.084 °F) |
| Boiling Point | 1032 K(758.85 °C, 1397.930 °F) |
| Critical Temperature | 2223 K |
| Superconducting Point | - |
Enthalpies of Potassium
| Heat of Fusion | 2.33 kJ/mol |
| Heat of Vaporization | 76.9 kJ/mol |
| Heat of Combustion | -182 J/(kg K) |
Potassium Isotopes - Nuclear Properties of Potassium
Potassium has 24 isotopes, with between 32 and 55 nucleons. Potassium has 2 stable naturally occuring isotopes.
Isotopes of Potassium - Naturally occurring stable Isotopes: 39K, 41K.
| Isotope | Z | N | Isotope Mass | % Abundance | T half | Decay Mode |
|---|---|---|---|---|---|---|
| 32K | 19 | 13 | 32 | Synthetic | ||
| 33K | 19 | 14 | 33 | Synthetic | ||
| 34K | 19 | 15 | 34 | Synthetic | ||
| 35K | 19 | 16 | 35 | Synthetic | ||
| 36K | 19 | 17 | 36 | Synthetic | ||
| 37K | 19 | 18 | 37 | Synthetic | ||
| 38K | 19 | 19 | 38 | Synthetic | ||
| 39K | 19 | 20 | 39 | 93.2581% | Stable | |
| 40K | 19 | 21 | 40 | 0.0117% | Stable | N/A |
| 41K | 19 | 22 | 41 | 6.7302% | Stable | N/A |
| 42K | 19 | 23 | 42 | Synthetic | ||
| 43K | 19 | 24 | 43 | Synthetic | ||
| 44K | 19 | 25 | 44 | Synthetic | ||
| 45K | 19 | 26 | 45 | Synthetic | ||
| 46K | 19 | 27 | 46 | Synthetic | ||
| 47K | 19 | 28 | 47 | Synthetic | ||
| 48K | 19 | 29 | 48 | Synthetic | ||
| 49K | 19 | 30 | 49 | Synthetic | ||
| 50K | 19 | 31 | 50 | Synthetic | ||
| 51K | 19 | 32 | 51 | Synthetic | ||
| 52K | 19 | 33 | 52 | Synthetic | ||
| 53K | 19 | 34 | 53 | Synthetic | ||
| 54K | 19 | 35 | 54 | Synthetic | ||
| 55K | 19 | 36 | 55 | Synthetic |
