Basics: protons/neutrons determine type of atom. Cations/anions determine gain or loss of valence electrons. Atomic mass is determined by protons and neutrons. Atomic number is determined by the number of protons. An element contains only atoms with the same atomic number. Elements can have isotopes which are atoms with a different number. Isomers have the same chemical formulas but different structures. Energy is stored in bonds between molecules and atoms. When energy is exchanged, heat is produced. Solution = solvent (ex. water) + solute (ex. sugar) Composed of a carbon chain and carboxyl group. The former is insoluble and the latter is soluble. Composed of: c, h, o, n and some s. There are twenty basic amino acids that are bound by peptide. Determined by amount, type and arrangement of. Result of folding within the alpha helices or. Ex. alpha helices, spirals, pleated sheets pleated sheets polypeptides.