Across
1
Precious yellow metallic element
4
Mass per unit volume
5
Glass that splits light into spectrum
6
Element found in all living things
8
Icy body with a tail near the sun
9
Disturbance that transfers energy
13
Group of similar cells
Down
2
Gas essential for breathing
3
Blocking of light by a celestial body
7
Ball of burning gas in space
8
Solid with repeating atomic pattern
10
Biological catalyst
11
Unit of force
12
Infectious microscopic agent