Notes

Introduction, Atoms and molecules (Lectures 1-3) Objectives Diagram the hierarchy of structural levels in biological organization (atom to Biosphere). (Atoms molecules, organelles, cell tissue, cell, organisms, population, communities, ecosystem, biosphere) Explain how the properties of life emerge from complex organization. (For humans: cell (tissue(organ(system(body) Distinguish between a hypothesis and a theory. (Hypothesis is an uncertain answer to a well framed question, a prediction that can be tested. Theory is supported by a lot of evidence and has exceptions and can be revised) Distinguish between an element and a compound. (Element is a substance that cannot be broken down into other substances by ordinary chemical procedures. Compound is a substance consisting of two or more elements in a fixed ratio NaCl) Identify the four elements that make up 96% of living matter and give an example of trace element. (Four elements: Oxygen, Nitrogen, Hydrogen, Carbon. Trace Element: Magnesium) Draw and label a simplified model of an atom. Explain how this model simplifies our understanding of atomic structure. Know the models for the six elements mentioned in class (C, H, O, N, P, S) Given the atomic number (memorize for the first 18 elements) and mass number of an atom, how do you determine the number of its neutrons' (Subtract the atomic number from the atomic mass) Explain how two isotopes of an element are similar. Explain how they are different. (Similar: same atomic number same # of protons. Different: diff atomic mass diff # of neutrons) Define the terms valence shell and valence electrons. Explain why the chemical properties of an element are mostly determined by its valence electrons.(V.S.: outermost area of an atom. V.E: an electron in the outer shell of an atom that can be transferred or shared.) Distinguish among nonpolar covalent, polar covalent and ionic bonds. (Nonpolar covalent bond: a bond where electrons are shared equally between two atoms. Polar covalent bond: where the electrons spend more time closer to the nucleus of the more electronegative atom. Ionic bond: the electrons are completely transferred from one atom to another rather than shared.) Describe a hydrogen bond and explain why weak bonds are important to living organisms.(hydrogen bond is the attractive force between the hydrogen attached to an electronegative atom of one molecule and an electronegative atom of a different molecule;these bonds can be broken and re-made fairly easily) With the use of a diagram or diagrams, explain why water molecules are polar. (The water molecule is polar because the shared electrons are closer to the oxygen atom rather than the hydrogen atoms.) Explain what is meant by a chemical equilibrium. (It is the point at which the rate of the forward reaction is equal to the rate of the reverse reaction.) Terms and Concepts Emergent properties, systems biology Matter, Element, Compound Common elements in living organisms Trace elements Atom Nucleus, Protons, Neutrons Electrons, Electron shell, Atomic number, Atomic Mass Unit (Dalton), Atomic weight Isotopes and Radioactive isotope Valence shell/valence electrons Chemical bonds, Covalent bond, Compound, Electronegativity, Polar and Nonpolar covalent bonds, Ionic bond, Ions, Cation, Anion, salts Weak chemical bonds Ionic bond (weak in water) Hydrogen bond van der Waals interactions Chemical reactions Reactants, Products, Chemical equilibrium