Across
1
Biological catalyst
4
Blocking of light by a celestial body
5
Compound containing oxygen
6
Element found in all living things
8
Particle of light
11
Precious yellow metallic element
Down
2
Fourth state of matter
3
Mass per unit volume
7
Unit of energy
9
Nerve cell in the brain
10
Solid with repeating atomic pattern
12
Icy body with a tail near the sun
13
Tissue that contracts for movement