| Element | Symbol | Atomic Number | Number of Atoms per Million Hydrogen Atoms |
| Hydrogen |
|
|
1,000,000
|
| Helium |
|
|
68,000
|
| Carbon |
|
|
420
|
| Nitrogen |
|
|
87
|
| Oxygen |
|
|
690
|
| Neon |
|
|
98
|
| Sodium |
|
|
2
|
| Magnesium |
|
|
40
|
| Aluminum |
|
|
3
|
| Silicon |
|
|
38
|
| Sulfur |
|
|
19
|
| Argon |
|
|
4
|
| Calcium |
|
|
2
|
| Iron |
|
|
34
|
| Nickel |
|
|
2
|
The elements are listed in order of increasing atomic number. The cosmic abundance of elements is the composition of the Sun and stars - and the cloud of interstellar gas from which the solar system is thought to have condensed. The "inert" elements, those which to not tend to combine with other elements are Helium, Neon and Argon.