Across
1
Center of an atom or cell
4
Molten rock beneath Earth surface
6
Element found in all living things
7
Particle of light
10
Form of thermal energy
11
Substance with pH above 7
13
Unit of energy
Down
2
Unit of heredity
3
Chemical element in table salt
5
Amplified beam of light
8
Mass per unit volume
9
Nerve cell in the brain
12
Substance with pH below 7