Across
1
Smallest unit of an element
4
Unit of energy
6
Mass per unit volume
7
Blocking of light by a celestial body
11
The Red Planet
Down
2
Naturally occurring inorganic solid
3
Biological catalyst
5
Infectious microscopic agent
8
Icy body with a tail near the sun
9
Push or pull on an object
10
Positive particle in nucleus
12
Reddish electrical conductor