Across
1
Positive particle in nucleus
5
Biological catalyst
6
Curved glass that refracts light
9
Magnetic metallic element
10
Solid with repeating atomic pattern
12
Group of similar cells
13
Measure of matter in an object
14
Precious yellow metallic element
Down
2
Mass per unit volume
3
Unit of force
4
Element found in all living things
7
Unit of electric potential
8
The Red Planet
11
Fourth state of matter
15
Center of an atom or cell