Compare Helium vs Xenon
Comparing Helium (He) and Xenon (Xe). Atomic numbers 2 and 54 with atomic masses 4.003 u and 131.294 u, classified as noble gas and noble gas. 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 | Xenon | |
|---|---|---|
| Symbol | He | Xe |
| Atomic number | 2 | 54 |
| Group | 18 | 18 |
| Period | 1 | 5 |
| Block | s | p |
| Element category | Noble Gas | Noble Gas |
Physical properties
| Helium | Xenon | |
|---|---|---|
| Phase at STP | Gas | Gas |
| Density | 0.1786 g/cm3 | 5.894 g/cm3 |
| Atomic weight | 4.0026 u | 131.294 u |
| Melting point | 0.95 K -272.2 °C -457.96 °F | 161.4 K -111.75 °C -169.15 °F |
| Boiling point | 4.222 K -268.928 °C -452.0704 °F | 165.051 K -108.099 °C -162.5782 °F |
Atomic properties
| Helium | Xenon | |
|---|---|---|
| Electronegativity (Pauling Scale) | 0 | 2.6 |
| Electron affinity | -48 kJ/mol | -77 kJ/mol |
| Oxidation states | 0 | 0, +1, +2, +4, +6, +8 (rarely more than 0; a weakly acidic oxide) |
| Ionization energies |
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Electron configuration
| Helium | Xenon | |
|---|---|---|
| Shorthand configuration | 1s2 | [Kr] 4d10 5s2 5p6 |
| Full configuration | 1s2 | 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p6 |
| Electrons per shell | 2 | 2, 8, 18, 18, 8 |
History
| Helium | Xenon | |
|---|---|---|
| Discovery | Pierre Janssen, Norman Lockyer (1868) | William Ramsay, Morris Travers (1898) |
| First isolation | William Ramsay, Per Teodor Cleve, Abraham Langlet (1895) | William Ramsay, Morris Travers (1898) |
| Named by | Edward Frankland, Norman Lockyer (1868) | William Ramsay (1898) |