Across
1
Gas form of a liquid
3
Curved glass that refracts light
4
Form of thermal energy
5
Gas essential for breathing
8
Solid with repeating atomic pattern
9
Substance with pH below 7
11
Element found in all living things
Down
2
Particle of light
6
Force that attracts objects together
7
Naturally occurring inorganic solid
10
Fourth state of matter