Across
1
The Red Planet
3
Magnetic metallic element
4
Curved glass that refracts light
8
Compound containing oxygen
10
Reddish electrical conductor
11
Tectonic landmass section
13
Mass per unit volume
Down
2
Center of an atom or cell
5
Unit of force
6
Path of a planet around the sun
7
Ball of burning gas in space
9
Basic unit of life
12
Biological catalyst