Across
1
Chemical element in table salt
3
Particle of light
4
Disturbance that transfers energy
5
Biological catalyst
8
Center of an atom or cell
9
Icy body with a tail near the sun
13
Glass that splits light into spectrum
Down
2
Group of similar cells
5
Blocking of light by a celestial body
6
Hottest planet in solar system
7
Mass per unit volume
9
Reddish electrical conductor
10
Amplified beam of light
11
Push or pull on an object
12
Unit of force