19K39.0983
Potassium
Alkali Metal
Solid at STP
Period 4Group 1Block SDiscovered 1807
[Ar]4s1
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.
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Atomic Properties
| Atomic Number | 19 |
| Atomic Mass | 39.0983 u |
| Electron Configuration | [Ar]4s1 |
| Oxidation States | +1 |
| Electronegativity | 0.82 (Pauling) |
| Atomic Radius | 275 pm |
| Ionization Energy | 4.341 eV |
| Electron Affinity | 0.501 eV |
| Block | S |
Physical Properties
| Appearance | silvery gray |
| Standard State | Solid |
| Melting Point | 336.53 K (63.4 °C) |
| Boiling Point | 1032 K (758.9 °C) |
| Density | 0.89 g/cm³ |
| Molar Heat | 29.6 J/(mol·K) |
| CPK Color | #8F40D4 |
Classification
| Category | Alkali Metal |
| Group Block | Alkali metal |
| Period | 4 |
| Group | 1 |
| Block | S |
Discovery
| Year Discovered | 1807 |
| Discovered By | Humphry Davy |
| Electron Shells | 2, 8, 8, 1 |