Across
1
Gas essential for breathing
3
Element found in all living things
4
Chemical element in table salt
6
Ball of burning gas in space
8
Hottest planet in solar system
Down
2
Icy body with a tail near the sun
3
Reddish electrical conductor
5
Amplified beam of light
7
Center of an atom or cell
9
Compound containing oxygen
10
Substance with pH below 7
11
Magnetic metallic element
12
Unit of energy