Atoms: are the lowest level of complexity in biology. 92 naturally occurring elements that were created in the stars. That"s how the galaxies, planets, moons were formed. 6 fundamental elements that all living things have- chnops. Matter and energy are one and the same- einsteins equation (e=mc^2) means matter and energy are different manifestations of the same thing. Potential energy is stored energy where we get into chemical bonds and interactions b/w atoms. Each organism doesn"t have the same amount of the 6 elements. An atom is made up of 3 main parts in nucleus are protons and neutrons which make up the mass. Each atom has its mass determined by amount of protons and neutrons. Radioactive isotopes can be separated bc of the mas difference. Protons determine properties of atoms- they determine how many electrons surround nucleus. Electons are negatively charged neutrons don"t have charge. Isotopes have same amount of protons but different amount of neutrons.