Across
1
Compound containing oxygen
4
Ball of burning gas in space
5
Absolute temperature scale unit
6
Icy body with a tail near the sun
7
Second lightest element
9
Particle of light
11
Smallest unit of an element
12
Substance with pH above 7
Down
2
Element found in all living things
3
Our home planet
8
Center of an atom or cell
9
Positive particle in nucleus
10
Blocking of light by a celestial body
13
Infectious microscopic agent
14
Basic unit of life