Across
1
Substance with pH below 7
3
Precious yellow metallic element
5
Curved glass that refracts light
7
Center of an atom or cell
8
Our home planet
Down
2
Compound containing oxygen
4
Measure of matter in an object
6
Tissue that contracts for movement
7
Unit of force
9
Particle of light
10
Blocking of light by a celestial body