Across
1
Path of a planet around the sun
3
Measure of matter in an object
6
Solid with repeating atomic pattern
7
Unit of force
9
Naturally occurring inorganic solid
Down
2
Element found in all living things
4
Mass per unit volume
5
Blocking of light by a celestial body
8
The Red Planet
10
Infectious microscopic agent
11
Smallest unit of an element
12
Gas essential for breathing
13
Positive particle in nucleus