The document discusses the basic levels of biological organization from atoms to organisms. It provides details on atomic structure, including the composition of the nucleus with protons and neutrons, and the orbiting electrons. Key concepts covered include chemical bonds, hydrogen bonding, and pH which are important foundations for understanding human biology.

2. Levels of Biological Organization atom molecule cell tissue organ organ system organism

6. Atomic mass = proton mass + neutron mass Atomic number = the number of protons All atoms of an element have the same number of protons atomic mass 4 atomic number 2 He atomic symbol