Across
1
Smallest unit of an element
4
Group of similar cells
5
Infectious microscopic agent
8
Gas essential for breathing
11
Disturbance that transfers energy
12
Unit of force
Down
2
Substance with pH above 7
3
Preserved remains of ancient life
6
Positive particle in nucleus
7
Nerve cell in the brain
9
Solid with repeating atomic pattern
10
Amplified beam of light