| Name | helium |
|---|---|
| Symbol | He |
| Atomic Weight | 4.002602 |
| Atomic Number | 2 |
| CAS ID | 7440-59-7 |
| Group Number | 18 |
| Group Name | Noble Gas |
| Period Number | 1 |
| Origin of Name | Greek, helios = "sun." |
| Year Discovered | 1895 |
| Discovery Credits | Isolated in 1895 by Sir William Ramsay at London, UK, and independently by P. T. Cleve and N. A. Langlet at Uppsala, Sweden. |
| Class | Non-Metallic |
| Color | Colorless |
| Standard State | Gas at 77 F & 298 K |
| Description | Colorless, odorless gas. Unreactive chemically. Used in deep-sea diving, weather balloons, and low temperature research instruments. Most natural sources of helium come from natural gas deposits where He is present from the alpha particle decay of heavy radioisotopes of U and Th and their daughter products. |