Across
1
Our home planet
3
Compound containing oxygen
5
Path of a planet around the sun
6
Infectious microscopic agent
7
Positive particle in nucleus
9
Disturbance that transfers energy
12
Curved glass that refracts light
Down
2
Element found in all living things
4
Force that attracts objects together
8
Push or pull on an object
10
Unit of electric potential
11
Biological catalyst
13
Particle of light