Across
1
Path of a planet around the sun
4
Our home planet
5
Particle of light
6
Absolute temperature scale unit
11
Center of an atom or cell
12
Chemical element in table salt
13
Measure of matter in an object
Down
2
Nerve cell in the brain
3
Compound containing oxygen
7
Mass per unit volume
8
Substance with pH below 7
9
Naturally occurring inorganic solid
10
Magnetic metallic element