Across
1
Fourth state of matter
3
Compound containing oxygen
4
The Red Planet
6
Unit of force
7
Center of an atom or cell
9
Gas form of a liquid
11
Force that attracts objects together
Down
2
Reddish electrical conductor
4
Tissue that contracts for movement
5
Particle of light
8
Glass that splits light into spectrum
10
Disturbance that transfers energy
12
Unit of energy
13
Icy body with a tail near the sun