Across
1
Force that attracts objects together
6
Mass per unit volume
8
Naturally occurring inorganic solid
10
Second lightest element
11
The Red Planet
Down
2
Measure of matter in an object
3
Glass that splits light into spectrum
4
Molten rock beneath Earth surface
5
Biological catalyst
7
Positive particle in nucleus
9
Center of an atom or cell
12
Particle of light