Across
1
Chemical element in table salt
4
Curved glass that refracts light
5
Unit of force
6
Biological catalyst
12
Tectonic landmass section
13
Substance with pH below 7
Down
2
Push or pull on an object
3
Nerve cell in the brain
7
Gas essential for breathing
8
Amplified beam of light
9
Center of an atom or cell
10
Naturally occurring inorganic solid
11
Unit of electric potential