Across
1
Center of an atom or cell
3
Smallest unit of an element
6
Chemical element in table salt
7
Gas form of a liquid
8
Element found in all living things
12
Basic unit of life
Down
2
Mass per unit volume
4
Molten rock beneath Earth surface
5
Ball of burning gas in space
9
Our home planet
10
Substance with pH above 7
11
Particle of light