Across
1
Measure of matter in an object
5
Form of thermal energy
6
Unit of energy
9
Center of an atom or cell
10
Unit of force
11
Path of a planet around the sun
13
Preserved remains of ancient life
Down
2
Icy body with a tail near the sun
3
Curved glass that refracts light
4
Chemical element in table salt
7
Basic unit of life
8
Hottest planet in solar system
12
Biological catalyst