Chemical element with atomic number 19 (K)
Potassium, 19 K Potassium pearls (in paraffin oil, ~5 mm each)
Appearance silvery white, faint bluish-purple hue when exposed to air
Atomic number (Z ) 19 Group group 1: hydrogen and alkali metals Period period 4 Block s-block Electron configuration [Ar ] 4s1 Electrons per shell 2, 8, 8, 1 Phase at STP solid Melting point 336.7 K (63.5 °C, 146.3 °F) Boiling point 1030.793 K (757.643 °C, 1395.757 °F)[3] Density (at 20° C) 0.8590 g/cm3 [4] when liquid (at m.p. ) 0.82948 g/cm3 [3] Critical point 2223 K, 16 MPa[5] Heat of fusion 2.33 kJ/mol Heat of vaporization 76.9 kJ/mol Molar heat capacity 29.6 J/(mol·K) Oxidation states −1, +1 basic oxide) Electronegativity Pauling scale: 0.82 Ionization energies 1st: 418.8 kJ/mol 2nd: 3052 kJ/mol 3rd: 4420 kJ/mol (more ) Atomic radius empirical: 227 pm Covalent radius 203±12 pm Van der Waals radius 275 pm Spectral lines of potassiumNatural occurrence primordial Crystal structure body-centered cubic (bcc) (cI2 ) Lattice constant a = 532.69 pm (at 20 °C)[4] Thermal expansion × 10−6 [4] Thermal conductivity 102.5 W/(m⋅K) Electrical resistivity 72 nΩ⋅m (at 20 °C) Magnetic ordering paramagnetic[6] Molar magnetic susceptibility × 10−6 3 /mol (298 K)[7] Young's modulus 3.53 GPa Shear modulus 1.3 GPa Bulk modulus 3.1 GPa Speed of sound thin rod 2000 m/s (at 20 °C) Mohs hardness 0.4 Brinell hardness 0.363 MPa CAS Number 7440-09-7 Discovery and first isolationHumphry Davy (1807)Symbol "K": from New Latin kalium
Category: Potassium references
child table, as reused in {IB-K}
References These references will appear in the article, but this list appears only on this page.
^ "Standard Atomic Weights: Potassium" . CIAAW . 1979.^ Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; Böhlke, John K.; Chesson, Lesley A.; Coplen, Tyler B.; Ding, Tiping; Dunn, Philip J. H.; Gröning, Manfred; Holden, Norman E.; Meijer, Harro A. J. (2022-05-04). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)" . Pure and Applied Chemistry . doi :10.1515/pac-2019-0603 . ISSN 1365-3075 . ^ 3.0 3.1 Aitken, F.; Volino, F. (January 2022). "New equations of state describing both the dynamic viscosity and self-diffusion coefficient for potassium and thallium in their fluid phases". Physics of Fluids . 34 (1): 017112. doi :10.1063/5.0079944 . ^ 4.0 4.1 4.2 Arblaster, John W. (2018). Selected Values of the Crystallographic Properties of Elements . Materials Park, Ohio: ASM International. ISBN 978-1-62708-155-9 ^ Haynes, William M., ed. (2011). CRC Handbook of Chemistry and Physics CRC Press . p. 4.122. ISBN 1-4398-5511-0 ^ Magnetic susceptibility of the elements and inorganic compounds , in Lide, D. R., ed. (2005). CRC Handbook of Chemistry and Physics (86th ed.). Boca Raton (FL): CRC Press. ISBN 0-8493-0486-5 ^ Weast, Robert (1984). CRC, Handbook of Chemistry and Physics . Boca Raton, Florida: Chemical Rubber Company Publishing. pp. E110. ISBN 0-8493-0464-4 One of these is a named reference . It may be cited in the containing article as
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