Across
1
Biological catalyst
4
Precious yellow metallic element
6
Solid with repeating atomic pattern
8
Smallest unit of an element
9
Unit of force
10
Icy body with a tail near the sun
Down
2
Gas essential for breathing
3
The Red Planet
4
Force that attracts objects together
5
Unit of energy
7
Substance with pH above 7
11
Group of similar cells
12
Measure of matter in an object