Across
1
Form of thermal energy
3
Element found in all living things
6
Gas form of a liquid
7
Particle of light
8
Second lightest element
9
Basic unit of life
10
Biological catalyst
13
Infectious microscopic agent
Down
2
Smallest unit of an element
4
Center of an atom or cell
5
Icy body with a tail near the sun
11
Positive particle in nucleus
12
Substance with pH above 7