Compare Lithium vs Potassium
Comparing Lithium (Li) and Potassium (K). Atomic numbers 3 and 19 with atomic masses 6.938 u and 39.098 u, classified as alkali metal and alkali metal. Below: a side-by-side comparison of their physical, atomic, electron-configuration and historical properties, including density, melting and boiling points, ionization energies, oxidation states and discovery history.
Periodic properties of the elements
| Lithium | Potassium | |
|---|---|---|
| Symbol | Li | K |
| Atomic number | 3 | 19 |
| Group | 1 | 1 |
| Period | 2 | 4 |
| Block | s | s |
| Element category | Alkali Metal | Alkali Metal |
Physical properties
| Lithium | Potassium | |
|---|---|---|
| Phase at STP | Solid | Solid |
| Density | 0.534 g/cm3 | 0.862 g/cm3 |
| Atomic weight | 6.938 u | 39.0983 u |
| Melting point | 453.65 K 180.5 °C 356.9 °F | 336.7 K 63.55 °C 146.39 °F |
| Boiling point | 1603 K 1329.85 °C 2425.73 °F | 1032 K 758.85 °C 1397.93 °F |
Atomic properties
| Lithium | Potassium | |
|---|---|---|
| Electronegativity (Pauling Scale) | 0.98 | 0.82 |
| Electron affinity | 59.6326 kJ/mol | 48.383 kJ/mol |
| Oxidation states | +1 (a strongly basic oxide) | −1, +1 (a strongly basic oxide) |
| Ionization energies |
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Electron configuration
| Lithium | Potassium | |
|---|---|---|
| Shorthand configuration | [He] 2s1 | [Ar] 4s1 |
| Full configuration | 1s2 2s1 | 1s2 2s2 2p6 3s2 3p6 4s1 |
| Electrons per shell | 2, 1 | 2, 8, 8, 1 |
History
| Lithium | Potassium | |
|---|---|---|
| Discovery | Johan August Arfwedson (1817) | Humphry Davy (1807) |
| First isolation | William Thomas Brande, Sir Humphrey Davy (1821) | Humphry Davy (1807) |