Across
1
Tectonic landmass section
4
Particle of light
5
Unit of energy
8
Center of an atom or cell
9
Naturally occurring inorganic solid
11
Positive particle in nucleus
12
Fourth state of matter
Down
2
Absolute temperature scale unit
3
Compound containing oxygen
6
Icy body with a tail near the sun
7
Preserved remains of ancient life
10
Our home planet