Across
1
Form of thermal energy
4
Magnetic metallic element
5
Mass per unit volume
6
Center of an atom or cell
9
Reddish electrical conductor
12
Unit of energy
Down
2
Positive particle in nucleus
3
Our home planet
7
Natural satellite of Earth
8
Solid with repeating atomic pattern
10
Biological catalyst
11
Unit of force
13
Ball of burning gas in space