Across
1
Curved glass that refracts light
4
Smallest unit of an element
5
Unit of electric potential
7
Our home planet
8
Glass that splits light into spectrum
10
Substance with pH below 7
11
Unit of heredity
Down
2
Second lightest element
3
Gas essential for breathing
6
Amplified beam of light
9
Icy body with a tail near the sun
12
Form of thermal energy