Potassium
Element 19 on the periodic table, symbol K, group 1, period 4.
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.
Appearance: silvery gray
Properties
- Atomic Number
- 19
- Atomic Mass
- 39.0983 u
- Group
- 1
- Period
- 4
- Block
- s-block
- Category
- Alkali Metal
- State at 25 °C
- Solid
- Melting Point
- 336.7 K · 63.6 °C
- Boiling Point
- 1,032 K · 758.9 °C
- Density
- 0.862 g/cm³
- Atomic Radius
- 220 pm
- Electronegativity
- 0.82
- Oxidation States
- +1
- Abundance in Crust
- 2.09e+4 mg/kg
- Discovered
- 1807
- Discovered By
- Humphry Davy
Electron Configuration
[Ar] 4s1
1s2 2s2 2p6 3s2 3p6 4s1
Ionisation Energies (kJ/mol)
- 1. 418.8
- 2. 3,052
- 3. 4,420
- 4. 5,877
- 5. 7,975
- 6. 9,590
- 7. 11,343
- 8. 14,944
Elements near Potassium
Elements in the same group share the number of outer electrons and behave in similar ways. Elements in the same period share a shell, so they change steadily from left to right.