Across
1
Form of thermal energy
4
Positive particle in nucleus
5
Amplified beam of light
6
Icy body with a tail near the sun
7
Biological catalyst
11
Absolute temperature scale unit
Down
1
Second lightest element
2
Substance with pH below 7
3
Unit of electric potential
5
Curved glass that refracts light
8
Force that attracts objects together
9
Path of a planet around the sun
10
Element found in all living things