Across
1
Positive particle in nucleus
4
Second lightest element
5
Force that attracts objects together
7
Mass per unit volume
Down
1
Particle of light
2
Absolute temperature scale unit
3
Ball of burning gas in space
6
Tissue that contracts for movement
8
Push or pull on an object
9
Preserved remains of ancient life
10
Compound containing oxygen
11
Disturbance that transfers energy