Across
1
Gas essential for breathing
4
Molten rock beneath Earth surface
5
Smallest unit of an element
6
Absolute temperature scale unit
7
Hottest planet in solar system
10
Center of an atom or cell
11
Second lightest element
13
Element found in all living things
Down
2
Chemical element in table salt
3
Icy body with a tail near the sun
8
Compound containing oxygen
9
Blocking of light by a celestial body
12
Unit of power
14
Measure of matter in an object