1. Atoms and Molecules 2.1 Elements and Atoms

2. Why do we need to study chemistry in a biology class?  Elements are _____  Matter is _____  Solid, liquid, gas  92 are natural  Six are basic for life  CHNOPS  Others: Na, K, Ca, Fe, Mg  Periodic table

3. What are atoms?  Smallest part of an _________  Important terms  Atomic symbol  Atomic mass (not weight)  Atomic number  Atomic particles include:  Electron shell

4. What is a mole?  Used as a standardizing unit  Avogadro’s number  6.023 X 10 23  We’ll play with this later…

5. What are isotopes?  Different number of ___  Same atomic _________  Different atomic ______  Sometimes radioactive  Used as a tracer (e.g. I)

6. How are electrons arranged in an atom?  Bohr diagrams  These show orbitals  1 st energy shell = ___ electrons  2 nd energy shell = ___ electrons  3 rd energy shell = ___ electrons  Octet rule  Determines bonding behavior  Two or more atoms bonded together = _______

7. Atoms and Molecules 2.2 Bonds form molecules

8. What is a molecule?  Two or more _______ sharing electrons  Molecules are the smallest form of a _______  Diatomic molecules  Several types of bonds  Ionic  Covalent  Polar  Non-polar  Hydrogen

9. What is an ionic bond?  One atom ______ an electron  Creates ions  Bond = attraction between opposite charges

10. What is a covalent bond?  Two atoms ________ electrons  Single  Double  Triple  Two types  Non-polar  Polar  Water is best example

11. What are hydrogen bonds?  Not a true bond  Due to the polar covalent nature of molecule

12. Atoms and Molecules 2.3 Properties of water

13. What are the properties of water?  Polar  Universal solvent  Cohesion  Adhesion  High heat capacity  High surface tension  Solid water is less dense than liquid water

14. What is polarity again?  Other molecules may be defined as  Hydrophobic  hydrophilic

15. Why is water a good solvent?  First some terms  Solution = ______ + _____  Water is polar…

16. What is the difference between cohesion and adhesion?  Cohesion  Due to ____ bonding  Adhesion

17. What is high heat capacity and why is it important?  Calorie = amount of heat needed to raise ______ of water by ______.  Hydrogen bonds change melting and boiling points  Without hydrogen  Would melt at -100 degrees C  Would boil at -91 degrees C

18. What is high surface tension?  Due to hydrogen bonds

19. Why is it important that liquid water is more dense than solid water?

20. Atoms and Molecules 2.4 Acids, bases and pH

21. What is pH?  = -log[H + ]  pH scale  How was it created?

22. What are acidic solutions?  Donate________________

23. What are basic solutions?  Either take up ____ or release _____

24. What is a buffer?  Important in our blood!