Cosmic Abundances

Element Symbol Atomic Number Number of Atoms per Million Hydrogen Atoms
Hydrogen
H
1
1,000,000
Helium
He
2
68,000
Carbon
C
6
420
Nitrogen
N
7
87
Oxygen
O
8
690
Neon
Ne
10
98
Sodium
Na
11
2
Magnesium
Mg
12
40
Aluminum
Al
13
3
Silicon
Si
14
38
Sulfur
S
16
19
Argon
Ar
18
4
Calcium
Ca
20
2
Iron
Fe
26
34
Nickel
Ni
28
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.

Note that after hydrogen and helium, the next most abundant element is oxygen. When hydrogen and oxygen combine you get H2O - water - making water (usually frozen) the most abundant icy substance. Carbon and nitrogen are also abundant and reactive elements – they make the next most common "ices," carbon monoxide (CO), carbon dioxide (CO2), methane (CH4) and nitrogen (N2).