Across
1
Amplified beam of light
3
Biological catalyst
4
Substance with pH below 7
5
Center of an atom or cell
7
Substance with pH above 7
10
Smallest unit of an element
Down
1
Curved glass that refracts light
2
Mass per unit volume
6
Positive particle in nucleus
8
Fourth state of matter
9
Reddish electrical conductor