Across
1
Solid with repeating atomic pattern
4
Nerve cell in the brain
5
Substance with pH below 7
6
Fourth state of matter
8
Icy body with a tail near the sun
Down
2
Glass that splits light into spectrum
3
Molten rock beneath Earth surface
4
Center of an atom or cell
7
Gas form of a liquid
9
Curved glass that refracts light