Across
1
Element found in all living things
4
Smallest unit of an element
5
Compound containing oxygen
7
Second lightest element
11
Particle of light
Down
2
Unit of electric potential
3
Tissue that contracts for movement
6
Preserved remains of ancient life
7
Form of thermal energy
8
Group of similar cells
9
Amplified beam of light
10
Natural satellite of Earth
12
Mass per unit volume
13
Disturbance that transfers energy