Chapter 3 Chemistry of Living Things Review

Across

3. the basic unit of matter
4. the most common elements in the human body are oxygen, carbon, hydrogen and ________
7. atoms of the same kind
9. a type of compound that contains carbon
10. a combination of two or more molecules
11. the number of protons an atom has is called its atomic ________
12. when molecules move from where there are many to where there are few
13. when you add the number of protons and neutrons an atom has, you get its atomic _______

Down
1. a combination of two or more elements (example CO2)
2. positively charged particles in an atom
5. the diffusion of H2O molecules across a cell membrane
6. particles in an atom that have a negative charge
7. when the molecules of a substance are evenly spread throughout an area
8. particles in an atom that have a neutral charge