Across
1
Smallest unit of an element
3
Mass per unit volume
6
Ball of burning gas in space
8
Compound containing oxygen
9
Reddish electrical conductor
11
Nerve cell in the brain
Down
2
Element found in all living things
4
Group of similar cells
5
Magnetic metallic element
7
Unit of electric potential
8
Gas essential for breathing
10
Second lightest element