Potassium
Potassium is a soft, waxy, silvery reactive metal that is never found unbound in nature; an element (symbol K) with an atomic number of 19 and atomic weight of 39.0983. The symbol is derived from the Latin kalium.
| General | |
|---|---|
| Name, symbol, number | potassium, K, 19 |
| Chemical series | alkali metals |
| Group, period, block | 1, 4, s |
| Appearance | silvery white |
| Standard atomic weight | 39.0983(1)g·mol-1 |
| Electron configuration | [Ar] 4s1 |
| Electrons per shell | 2, 8, 8, 1 |
| Physical properties | |
| Phase | solid |
| Density (near r.t.) | 0.89 g·cm-3 |
| Liquid density at m.p. | 0.828 g·cm-3 |
| Melting point | 336.53 K (63.38 °C, 146.08 °F) |
| Boiling point | 1032 K (759 °C, 1398 °F) |
| Triple point | 336.35 K (63°C), kPa |
| Atomic properties | |
| Crystal structure | cubic body centered |
| Oxidation states | 1 (strongly basic oxide) |
| Electronegativity | 0.82 (Pauling scale) |
| Ionization energies (more) |
1st: 418.8 kJ·mol-1 |
| 2nd: 3052 kJ·mol-1 | |
| 3rd: 4420 kJ·mol-1 | |
| Atomic radius | 220 pm |
| Atomic radius (calc.) | 243 pm |
| Covalent radius | 196 pm |
| Van der Waals radius | 275 pm |
| Miscellaneous | |
| Magnetic ordering | paramagnetic |
| Thermal conductivity | (300 K) 102.5 W·m-1·K-1 |
| Thermal expansion | (25 °C) 83.3 µm·m-1·K-1 |
| Speed of sound (thin rod) | (20 °C) 2000 m/s |
| Young's modulus | 3.53 GPa |
| Shear modulus | 1.3 GPa |
| Bulk modulus | 3.1 GPa |
| Mohs hardness | 0.4 |
| Brinell hardness | 0.363 MPa |
| CAS registry number | 7440-09-7 |
Content from Wikipedia for educational use and displayed with permission under the GFDL.
Please report any inaccuracies to the Webmaster.
NEW! Allowable Levels Established for DEHP in Bottled Water
Vapor Intrusion Investigations: Air Sampling Tips for Meeting Data Quality Objectives
Incremental Sampling Methodology