| Element | Argon | Symbol | Ar |
| Atomic Number | 18 | Molar Mass | 39.95 gmol-1 |
| Electron Configuration | [Ne]3s23p6 | Normal State | gas nonmetal |
| Density @STP | 1.78x10-3 g cm-3 | Melting Point | -189oC |
| Boiling Point | -186oC | Stable Isotopes | 36Ar, 38Ar, 40Ar |
| Atomic Radius | 174 pm | Ionic Radius | n/a |
| Electronegativity (Pauling) | n/a | Ionization Energy (1st) | 1520 kJ mol-1 |
| Ionization Energy (2nd) | 2665 kJ mol-1 | Ionization Energy (3rd) | 3928 kJ mol-1 |
| Molar Heat Capacity | 20.8 J K-1mol-1 | Standard Molar Entropy | 154.8 J K-1mol-1 |
| Enthalpy of Fusion | 1.21 kJ mol-1 | Enthalpy of Vapourization | 6.53 kJ mol-1 |