Compare Helium vs Lithium
Comparing Helium (He) and Lithium (Li). Atomic numbers 2 and 3 with atomic masses 4.003 u and 6.938 u, classified as noble gas 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
| Helium | Lithium | |
|---|---|---|
| Symbol | He | Li |
| Atomic number | 2 | 3 |
| Group | 18 | 1 |
| Period | 1 | 2 |
| Block | s | s |
| Element category | Noble Gas | Alkali Metal |
Physical properties
| Helium | Lithium | |
|---|---|---|
| Phase at STP | Gas | Solid |
| Density | 0.1786 g/cm3 | 0.534 g/cm3 |
| Atomic weight | 4.0026 u | 6.938 u |
| Melting point | 0.95 K -272.2 °C -457.96 °F | 453.65 K 180.5 °C 356.9 °F |
| Boiling point | 4.222 K -268.928 °C -452.0704 °F | 1603 K 1329.85 °C 2425.73 °F |
Atomic properties
| Helium | Lithium | |
|---|---|---|
| Electronegativity (Pauling Scale) | 0 | 0.98 |
| Electron affinity | -48 kJ/mol | 59.6326 kJ/mol |
| Oxidation states | 0 | +1 (a strongly basic oxide) |
| Ionization energies |
|
|
Electron configuration
| Helium | Lithium | |
|---|---|---|
| Shorthand configuration | 1s2 | [He] 2s1 |
| Full configuration | 1s2 | 1s2 2s1 |
| Electrons per shell | 2 | 2, 1 |
History
| Helium | Lithium | |
|---|---|---|
| Discovery | Pierre Janssen, Norman Lockyer (1868) | Johan August Arfwedson (1817) |
| First isolation | William Ramsay, Per Teodor Cleve, Abraham Langlet (1895) | William Thomas Brande, Sir Humphrey Davy (1821) |
| Named by | Edward Frankland, Norman Lockyer (1868) |