Across
1
Biological catalyst
3
Form of thermal energy
5
Precious yellow metallic element
6
Ball of burning gas in space
8
Substance with pH above 7
10
Force that attracts objects together
Down
1
Our home planet
2
Smallest unit of an element
4
Gas essential for breathing
7
Hottest planet in solar system
9
Gas form of a liquid
11
Path of a planet around the sun