Across
1
Center of an atom or cell
6
Tissue that contracts for movement
8
Smallest unit of an element
9
Precious yellow metallic element
10
Biological catalyst
12
Particle of light
13
Preserved remains of ancient life
Down
2
Substance with pH above 7
3
Curved glass that refracts light
4
Push or pull on an object
5
Amplified beam of light
7
Second lightest element
11
Blocking of light by a celestial body