Across
1
Force that attracts objects together
4
Chemical element in table salt
6
Ball of burning gas in space
8
Basic unit of life
10
Push or pull on an object
Down
2
Unit of electric potential
3
The Red Planet
5
Path of a planet around the sun
7
Compound containing oxygen
8
Icy body with a tail near the sun
9
Infectious microscopic agent
11
Center of an atom or cell
12
Positive particle in nucleus