Compare Helium vs Radon
Comparing Helium (He) and Radon (Rn). Atomic numbers 2 and 86 with atomic masses 4.003 u and 222 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 | Radon | |
|---|---|---|
| Symbol | He | Rn |
| Atomic number | 2 | 86 |
| Group | 18 | 18 |
| Period | 1 | 6 |
| Block | s | p |
| Element category | Noble Gas | Noble Gas |
Physical properties
| Helium | Radon | |
|---|---|---|
| Phase at STP | Gas | Gas |
| Density | 0.1786 g/cm3 | 9.73 g/cm3 |
| Atomic weight | 4.0026 u | 222 u |
| Melting point | 0.95 K -272.2 °C -457.96 °F | 202 K -71.15 °C -96.07 °F |
| Boiling point | 4.222 K -268.928 °C -452.0704 °F | 211.5 K -61.65 °C -78.97 °F |
Atomic properties
| Helium | Radon | |
|---|---|---|
| Electronegativity (Pauling Scale) | 0 | 2.2 |
| Electron affinity | -48 kJ/mol | -68 kJ/mol |
| Oxidation states | 0 | 0, +2, +6 () |
| Ionization energies |
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Electron configuration
| Helium | Radon | |
|---|---|---|
| Shorthand configuration | 1s2 | [Xe] 4f14 5d10 6s2 6p6 |
| Full configuration | 1s2 | 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 6s2 6p6 |
| Electrons per shell | 2 | 2, 8, 18, 32, 18, 8 |
History
| Helium | Radon | |
|---|---|---|
| Discovery | Pierre Janssen, Norman Lockyer (1868) | Ernest Rutherford, Robert Bowie Owens (1899) |
| First isolation | William Ramsay, Per Teodor Cleve, Abraham Langlet (1895) | William Ramsay, Robert Whytlaw-Gray (1910) |
| Named by | Edward Frankland, Norman Lockyer (1868) |