Across
1
Smallest unit of an element
3
Particle of light
4
Substance with pH below 7
5
Absolute temperature scale unit
6
Solid with repeating atomic pattern
8
Hottest planet in solar system
11
Substance with pH above 7
Down
2
Tissue that contracts for movement
3
Fourth state of matter
7
Natural satellite of Earth
9
Nerve cell in the brain
10
Precious yellow metallic element
12
Biological catalyst