Across
1
Particle of light
4
Curved glass that refracts light
5
Solid with repeating atomic pattern
7
Biological catalyst
9
Gas essential for breathing
10
Reddish electrical conductor
11
Tissue that contracts for movement
Down
1
Positive particle in nucleus
2
Unit of force
3
Magnetic metallic element
6
Path of a planet around the sun
8
Mass per unit volume
10
Basic unit of life