Across
1
Path of a planet around the sun
3
Center of an atom or cell
4
Second lightest element
7
Tectonic landmass section
8
Unit of force
9
Disturbance that transfers energy
10
Glass that splits light into spectrum
12
Chemical element in table salt
Down
2
Group of similar cells
5
Smallest unit of an element
6
Gas essential for breathing
10
Particle of light
11
Element found in all living things
13
The Red Planet