Across
1
Glass that splits light into spectrum
3
Absolute temperature scale unit
6
Gas essential for breathing
7
Basic unit of life
8
Center of an atom or cell
9
Preserved remains of ancient life
11
Second lightest element
Down
2
Magnetic metallic element
4
Blocking of light by a celestial body
5
Naturally occurring inorganic solid
10
Biological catalyst
12
Nerve cell in the brain
13
Element found in all living things