Across
1
Curved glass that refracts light
4
Smallest unit of an element
5
Tissue that contracts for movement
6
Absolute temperature scale unit
8
Chemical element in table salt
9
Fourth state of matter
12
Mass per unit volume
Down
2
Second lightest element
3
Group of similar cells
5
Naturally occurring inorganic solid
7
Blocking of light by a celestial body
10
Element found in all living things
11
Unit of electric potential