BIOL 1107 Lecture Notes - Lecture 1: Hemoglobin, Work Function, Electronegativity
Document Summary
Life uses only about 20 of the 123 elements. Oxygen is the most common element in earth"s crust, it is also the most common element used by living things. Silicon is the second most common element in earth"s crust (but life uses carbon instead because it is easier to bond with) Most elements on the periodic table are not needed for life, ex: neon- if neon was used for life we would glow. The elements that are not used are unreactive (have a full valence shell) Life only uses reactive elements (don"t have a full valence shell) Reactive elements bond to form complex substances. Incomplete orbitals are reactive because they are looking for an electron to bond with. Hydrogen bonds are not chemical bonds, they are electrostatic attractions. Chemical bonds involve electrons within atoms to make new substances. If electrons are not involved, it is not a chemical bond. Covalent and ionic bonds are chemical bonds.
