Across
1
Unit of electric potential
3
Biological catalyst
4
Center of an atom or cell
6
Natural satellite of Earth
7
Solid with repeating atomic pattern
8
Tissue that contracts for movement
11
Unit of energy
Down
2
Absolute temperature scale unit
5
Nerve cell in the brain
8
Measure of matter in an object
9
Gas essential for breathing
10
Substance with pH above 7
12
Force that attracts objects together
13
Curved glass that refracts light