Across
1
Nerve cell in the brain
3
Disturbance that transfers energy
7
Amplified beam of light
8
Substance with pH above 7
9
Smallest unit of an element
10
Glass that splits light into spectrum
12
Magnetic metallic element
Down
2
Gas essential for breathing
4
Mass per unit volume
5
Center of an atom or cell
6
The Red Planet
11
Force that attracts objects together