Across
1
Biological catalyst
5
Positive particle in nucleus
6
Nerve cell in the brain
8
The Red Planet
9
Substance with pH below 7
11
Second lightest element
Down
2
Unit of energy
3
Unit of heredity
4
Center of an atom or cell
7
Magnetic metallic element
10
Gas form of a liquid
12
Absolute temperature scale unit
13
Push or pull on an object