Across
1
The Red Planet
2
Form of thermal energy
4
Path of a planet around the sun
8
Force that attracts objects together
10
Amplified beam of light
Down
2
Second lightest element
3
Smallest unit of an element
5
Measure of matter in an object
6
Solid with repeating atomic pattern
7
Group of similar cells
8
Unit of heredity
9
Gas form of a liquid