Across
1
Precious yellow metallic element
3
Particle of light
5
Nerve cell in the brain
6
Chemical element in table salt
9
Form of thermal energy
Down
2
Curved glass that refracts light
4
Second lightest element
7
Smallest unit of an element
8
Compound containing oxygen
10
Icy body with a tail near the sun
11
Magnetic metallic element