Helium
Electron Configuration
|
General Properties
| Atomic Symbol | He |
| Atomic Weight | 4.00260 g/mol |
| Element Number | 2 |
| Standard State | Gas |
| Standard Type | Neutral |
| Date of Discovery | 1868 |
| Discoverer | Lockyer |
Physical Properties
| Oxidation States | -- |
| Boiling Point | 4.216 K |
| Melting Point | 0.95 K |
| Density | 0.1785 (Gas 273K g/l) |
| Electron Configuration | 1s2 |
| Acid/Base Properties | -- |
| Crystal Structure | Hexagonal |
| Electronegativity | -- |
| Heat of Vaporization | 0.084 kJ/mol |
| Heat of Fusion | 0.021 kJ/mol |
| Electrical Conductivity | -- |
| Thermal Conductivity | 0.152 Wm-¹K-¹ (at 300 K) |
| Specific Heat Capacity | 5.193 Jg-¹K-¹ (at 300 K) |
| First Ionization Potential | 24.587 |
| Atomic Volume | 31.80 cm³/mol |
| Atomic Radius | 1.88 Å |
| Covalent Radius | 0.93 Å |
| Synthetic | No |