Across
1
Biological catalyst
3
Measure of matter in an object
5
Nerve cell in the brain
8
Unit of power
9
Form of thermal energy
10
Unit of force
12
Group of similar cells
Down
2
Chemical element in table salt
4
Second lightest element
5
Center of an atom or cell
6
Smallest unit of an element
7
Icy body with a tail near the sun
11
Gas form of a liquid