Bio 151 1st Edition Lecture 3 Outline of Last Lecture I Scientific Inquiry and The Unifying Themes of Biology Outline of Current Lecture II Atomic Structure Chapter 2 III Atoms IV Periodic Table V Hydrogen Bonds Current Lecture Chapter 2 Atomic Structure Approximately 13 billion years ago Big Bang Started our universe 4 5 billion Earth 3 5 billion Life on Earth Matter anything that has mass and occupies space Nucleus contains protons and neutrons Orbital contains electrons Energy Levels K 1st level 1 orbital 2 electrons L 2nd level 2 3 orbitals 2 electrons per orbital M 3rd level 2 3 orbitals 2 electrons per orbital These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Atoms Atomic Number number of protons in the nucleus Determines order on the Periodic Table Atomic Mass number of protons and neutrons in the nucleus Mass measures matter Weight measure the gravitational pull on an object or substance Neutral atoms have equal protons and neutrons or more neutrons than protons Neutral atoms are also called isotopes Ex Carbon C P 6 N 6 C12 Carbon 12 most common isotope Equal protons and electrons Neutral charge More protons than electrons Positive charge More electrons than protons Negative charge Ion atom with a different number of protons and electrons Atoms are measure in units of Daltons 6 02x10 23 Daltons 1 gram P N 1 Dalton Electron 1 2000 Dalton Negative charges are attracted to protons Valence electrons are electrons in the outer most shell Oxidation loss of electrons Reduction gain of electrons Octet Rule Valence shell is full Atom is stable Does not want to react 8 electrons in outer shell Exceptions Hydrogen H and Helium He Periodic Table Columns 1 2 6 and 7 form ionic bonds Transfer of electrons LiF Columns 3 and 4 form covalent bonds Sharing electrons O2 Electronegativity attraction of an atom for electrons 12 atoms that are in ALL LIVING THINGS 1 Carbon C 2 Hydrogen H 3 Oxygen O 4 Nitrogen N 5 Phosphorus P 6 Sulfur S 7 Chloride Cl 8 Calcium Ca 9 Iron Fe 10 Magnesium Mg 11 Sodium Na 12 Potassium K 2 atoms found in trace amounts in ALL LIVING THINGS 1 Iodine I 2 Zinc Zn Hydrogen Bonds Special covalent bonds polar Temperature a Increased heat Increased movement Increased reaction pH Nature Bonding Catalysts a Enzymes stabilize or stress The energy from the activation on catalysts can either ease the formation of bonds or ease the breakage of bonds