Across
1
Second lightest element
5
Naturally occurring inorganic solid
6
Element found in all living things
7
Curved glass that refracts light
9
Smallest unit of an element
11
Disturbance that transfers energy
Down
2
Center of an atom or cell
3
Magnetic metallic element
4
Molten rock beneath Earth surface
8
Form of thermal energy
10
Ball of burning gas in space
12
Biological catalyst
13
Unit of heredity