Across
1
Chemical element in table salt
3
Positive particle in nucleus
5
Smallest unit of an element
7
Mass per unit volume
8
Our home planet
9
Measure of matter in an object
12
Push or pull on an object
Down
2
Unit of electric potential
3
Fourth state of matter
4
Substance with pH below 7
6
Naturally occurring inorganic solid
10
Ball of burning gas in space
11
Gas essential for breathing