Across
1
Second lightest element
4
Unit of force
5
Unit of electric potential
6
Absolute temperature scale unit
9
Form of thermal energy
11
Center of an atom or cell
13
Amplified beam of light
Down
2
Our home planet
3
Tectonic landmass section
7
Gas form of a liquid
8
Curved glass that refracts light
10
Naturally occurring inorganic solid
12
Particle of light