Helium vs Fluorine
| Property | He Helium | F Fluorine |
|---|---|---|
| Atomic number | 2 | 9 |
| Symbol | He | F |
| Name | Helium | Fluorine |
| Category | noble-gas | halogen |
| Standard Atomic Weight | 4.002602 u | 18.998403 u |
| Period | 1 | 2 |
| Group | 18 | 17 |
| Block | s | p |
| Phase at STP | gas | gas |
| Electron configuration | 1s2 | [He]2s22p5 |
| Oxidation states | [0] | -1 |
| Electronegativity (Pauling) | N/A | 3.98 |
| Electron affinity | -0.5 eV | 3.4011 eV |
| Density | 0.1785 kg/m³ | 1.696 kg/m³ |
| Melting point | -272.2 °C | -219.62 °C |
| Boiling point | -268.93 °C | -188.12 °C |
| Discovery year | 1868 | 1886 |