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chemistry

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chemistry

  1. 1. Human Biology (BI 104-01) <ul><li>Instructor: Dr. Zhe Xu </li></ul><ul><li>[email_address] </li></ul>
  2. 2. Levels of Biological Organization atom molecule cell tissue organ organ system organism
  3. 3. Basic Chemistry (Inorganic) <ul><li>Atom </li></ul><ul><ul><li>Atoms are the basic units of elements </li></ul></ul><ul><ul><li>96% of human body: OCHN </li></ul></ul>Periodic Table of The Elements
  4. 4. <ul><ul><li>Each atom consists of a nucleus and orbiting electrons </li></ul></ul>Helium (He) nucleus electron
  5. 5. <ul><ul><ul><li>Nucleus </li></ul></ul></ul><ul><ul><ul><ul><li>Proton: “+” charged, atomic mass = 1 unit </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Neutron: uncharged, atomic mass = 1 unit </li></ul></ul></ul></ul><ul><ul><ul><li>Electron shell </li></ul></ul></ul><ul><ul><ul><ul><li>Electrons: “-” charged, atomic mass  0 unit </li></ul></ul></ul></ul>Atoms are electrically neutral
  6. 6. Atomic mass = proton mass + neutron mass Atomic number = the number of protons All atoms of an element have the same number of protons atomic mass 4 atomic number 2 He atomic symbol
  7. 7. <ul><ul><li>Isotopes </li></ul></ul><ul><ul><ul><li>Atoms of the same element that differ in the number of neutrons </li></ul></ul></ul>(radioactive) 12 6 Carbon 12 C 13 6 Carbon 13 C 14 6 Carbon 14 C 14 7 Nitrogen 14 N decay
  8. 8. <ul><ul><li>Electron shells </li></ul></ul><ul><ul><ul><li>The innermost shell holds up to 2 electrons. </li></ul></ul></ul><ul><ul><ul><li>The outermost shell (valence shell) is most stable with 8 electrons (rule of eights) </li></ul></ul></ul>
  9. 9. <ul><li>Chemical bonds </li></ul><ul><ul><li>Ionic bond </li></ul></ul><ul><ul><li>Electrons are transferred from one atom to another </li></ul></ul><ul><ul><ul><li>Anion: gain electrons, negatively charged </li></ul></ul></ul><ul><ul><ul><li>Cation: lose electrons, positively charged </li></ul></ul></ul>
  10. 11. <ul><ul><li>Covalent bond: share electrons between atoms to meet the rule of eights </li></ul></ul>hydrogen gas (H 2 ) oxygen gas (O 2 ) water (H 2 O) nonpolar polar
  11. 12. <ul><ul><li>Hydrogen bond: attraction between electropositive H and electronegative O or N. </li></ul></ul>polar molecule
  12. 13. <ul><li>Properties of H 2 O: all attribute to hydrogen bond </li></ul><ul><ul><li>High heat capacity: </li></ul></ul><ul><ul><ul><li>Water temperature rises and falls slowly </li></ul></ul></ul><ul><ul><li>High heat of vaporization: </li></ul></ul><ul><ul><ul><li>Vaporization of water requires lots of heat </li></ul></ul></ul><ul><ul><li>Solvent: </li></ul></ul><ul><ul><ul><li>Dissolves ionized and polar molecules </li></ul></ul></ul><ul><ul><li>Cohesive and adhesive: </li></ul></ul><ul><ul><ul><li>Water molecules adhere to each other and polar surfaces </li></ul></ul></ul><ul><ul><li>High surface tension: </li></ul></ul><ul><ul><li>Ice is less dense than liquid H 2 O </li></ul></ul>
  13. 14. <ul><li>Buffer </li></ul><ul><li>A chemical or a combination of chemicals that keeps pH within normal limits, usually weak acids or weak bases. </li></ul><ul><ul><li>Acids </li></ul></ul><ul><ul><ul><li>Dissociate in water and release H + </li></ul></ul></ul><ul><ul><ul><li>Strong acid: Dissociation is almost complete. </li></ul></ul></ul><ul><ul><ul><li>HCl -> H + + Cl - </li></ul></ul></ul><ul><ul><ul><li>Weak acid: Dissociation is minimal. </li></ul></ul></ul>(carbonic acid) (bicarbonate ion) <ul><ul><li>H 2 CO 3 H + + HCO 3 - </li></ul></ul>
  14. 15. <ul><ul><li>Bases </li></ul></ul><ul><ul><ul><li>Either take up H + or release OH - </li></ul></ul></ul><ul><ul><ul><li>Strong base: Dissociation is almost complete </li></ul></ul></ul><ul><ul><li>NaOH -> Na + + OH - </li></ul></ul><ul><ul><ul><li>Weak base: Dissociation is minimal </li></ul></ul></ul>ammonia ammonium ion <ul><ul><li>NH 3 + H 2 O NH 4 + + OH - </li></ul></ul>
  15. 16. <ul><ul><li>pH scale </li></ul></ul><ul><ul><ul><li>Measurement scale for hydrogen ion concentration </li></ul></ul></ul><ul><ul><ul><li>pH = -(log 10 [H + ]) </li></ul></ul></ul>0 7 14 acid base [H + ] (moles per liter) pH 1 x 10 -6 6 1 x 10 -7 7 1 x 10 -8 8
  16. 17. Study Guide <ul><li>Which four element make up the bulk of living matter? </li></ul><ul><li>Name the elements: O, C, H, N, Ca, P, K, Na, Cl, I, Fe. </li></ul><ul><li>What is the nucleus of an atom composed of? </li></ul><ul><li>What type of charge do protons carry? </li></ul><ul><li>Do neutrons have charge? </li></ul><ul><li>What type of charge do electrons carry? </li></ul><ul><li>What is the atomic number? </li></ul><ul><li>What is the atomic mass? </li></ul><ul><li>What are isotopes? </li></ul><ul><li>An atom is inert when its valence shell contain ____ electrons. </li></ul><ul><li>What type of chemical bond exists in table salt (NaCl) and O 2 ? </li></ul><ul><li>What type of chemical bond contributes to the special properties of water? </li></ul><ul><li>What is the scale of pH? What pH is acidic? What pH is alkaline? </li></ul>

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