Across
1
Unit of energy
3
Precious yellow metallic element
5
Blocking of light by a celestial body
6
Smallest unit of an element
10
Tissue that contracts for movement
Down
2
Center of an atom or cell
4
Amplified beam of light
7
Substance with pH below 7
8
Element found in all living things
9
Positive particle in nucleus
11
The Red Planet