Across
1
Force that attracts objects together
2
Gas essential for breathing
3
Curved glass that refracts light
5
Blocking of light by a celestial body
7
Measure of matter in an object
10
Infectious microscopic agent
11
Substance with pH below 7
12
Ball of burning gas in space
Down
2
Compound containing oxygen
4
Solid with repeating atomic pattern
6
Second lightest element
8
Particle of light
9
Disturbance that transfers energy