Across
1
Tectonic landmass section
4
Center of an atom or cell
5
Compound containing oxygen
6
Smallest unit of an element
7
Hottest planet in solar system
12
Chemical element in table salt
Down
1
Positive particle in nucleus
2
Unit of heredity
3
Preserved remains of ancient life
8
Gas essential for breathing
9
Our home planet
10
Tissue that contracts for movement
11
Glass that splits light into spectrum