Across
1
Smallest unit of an element
3
Positive particle in nucleus
4
Path of a planet around the sun
8
Infectious microscopic agent
9
Precious yellow metallic element
10
Tissue that contracts for movement
Down
2
Reddish electrical conductor
5
Measure of matter in an object
6
Gas essential for breathing
7
Chemical element in table salt
11
Form of thermal energy
12
The Red Planet
13
Naturally occurring inorganic solid