Helium vs Arsenic
| Property | He Helium | As Arsenic |
|---|---|---|
| Atomic number | 2 | 33 |
| Symbol | He | As |
| Name | Helium | Arsenic |
| Category | noble-gas | metalloid |
| Standard Atomic Weight | 4.002602 u | 74.921595 u |
| Period | 1 | 4 |
| Group | 18 | 15 |
| Block | s | p |
| Phase at STP | gas | solid |
| Electron configuration | 1s2 | [Ar]4s23d104p3 |
| Oxidation states | [0] | [-3, -2, -1, 0, 1, 2, 3, 4, 5] |
| Electronegativity (Pauling) | N/A | 2.18 |
| Electron affinity | -0.5 eV | 0.81 eV |
| Density | 0.1785 kg/m³ | 5776 kg/m³ |
| Melting point | -272.2 °C | 816.85 °C |
| Boiling point | -268.93 °C | 613.85 °C |
| Discovery year | 1868 | 1250 |