1. Lab 1 – Introduction to biological sciences No quiz or worksheet due today

2. Outline of today’s lab Atoms –What are they made of? –What makes different atoms different? –How are ions and anions formed? pH –What is it? –What is the pH of various solutions? –What are buffers? Using the metric system –Practicing measurements / unit conversions.

3. Atoms! Composed of protons, neutrons, and electrons –Protons = +1 charge –Electrons = -1 charge –Neutrons = neutral Bohr Model is the classic model –Protons and neutrons in the nucleus –Electrons in shells around the nucleus B 10.81 Boron 5 5 protons 6 neutrons Bohr model of Boron Periodic table ccasa by Armtuk http://commons.wikimedia.org/wiki/Image:Periodic_Table_Armtuk3.svg; Boron art by Marc Perkins

4. How do we figure out what’s in each atom? Protons –# protons = Atomic number Neutrons –# neutrons = Atomic mass - # protons Unless it’s an isotope Electrons –# electrons = # protons Unless it’s an ion B 10.81 Boron 5 5 protons 6 neutrons Atomic number Atomic mass

5. Ions: gaining or losing electrons Salt –NaCl –Sodium Chloride Na and Cl become ions –Na loses an electron –Cl gains an electron Written as –Na + –Cl - 11 protons 11 electrons 11 protons 10 electrons 17 protons 17 electrons 17 protons 18 electrons Chlorine atom (Cl) Sodium atom (Na) Chlorine atom (Cl - ) Sodium atom (Na + )

6. The periodic table Periodic table ccasa by Armtuk http://commons.wikimedia.org/wiki/Image:Periodic_Table_Armtuk3.svg; Boron art by Marc Perkins

7. Outline of today’s lab Atoms –What are they made of? –What makes different atoms different? –How are ions and anions formed? pH –What is it? –What is the pH of various solutions? –What are buffers? Using the metric system –Practicing measurements / unit conversions

8. Acidity Completely dependent on the concentration of protons (H + ) in solution –The more protons (H + ), the more acidic –The more things that absorb protons (e.g., OH - ), the more basic Lots of protons (H + )Highly BasicHighly AcidicFew protons (H + ) pH Scale ccasa by Slower http://commons.wikimedia.org/wiki/Image:PH_scale.png

9. Acid Base (hydrochloric acid) (sodium hydroxide / lye)

10. pH Scale ccasa by Slower http://commons.wikimedia.org/wiki/Image:PH_scale.png pH’s of common items Lots of protons (H + )Highly BasicHighly AcidicFew protons (H + )

11. Buffers Chemicals that maintain a constant pH in a solution, even when acid or base is added Example: Bicarbonate (NaHCO 3 ) –In solution dissociates into Na + and (HCO 3 ) - If we add an acid (H + ) If we add a base (OH - ) Bicarbonate absorbs the proton!Bicarbonate produces a proton! (that will react with OH- to form H2O)

12. Outline of today’s lab Atoms –What are they made of? –What makes different atoms different? –How are ions and anions formed? pH –What is it? –What is the pH of various solutions? –What are buffers? Using the metric system –Practicing measurements / unit conversions

13. Measuring volume Use the pipettes, graduated cylinders, or the scale –1 ml H 2 O = 1g Meniscus diagram gnu FDL by Jleedev: http://en.wikipedia.org/wiki/Image:Reading_the_meniscus.png Read the volume at the bottom of the meniscus

14. The periodic table Periodic table ccasa by Armtuk http://commons.wikimedia.org/wiki/Image:Periodic_Table_Armtuk3.svg; Boron art by Marc Perkins

15. Before you leave Clean up your work area –Wash glassware and store upside down Show me your lab report so I can stamp it –Need to have all data fields filled in –Complete at home and then turn in at the beginning of next lab Remember that we’ll have a quiz at the beginning of the next class –6-7 questions on today’s lab –3-4 questions on the lab we’ll do next week

16. Notes for the instructor: If you need a screen-displayable periodic table that shows atomic masses, try this one by the IUPAC: –http://www.iupac.org/reports/periodic_table/

17. License information This work is licensed under the Creative Commons Attribution- NonCommercial-ShareAlike 3.0 License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc- sa/3.0/us/ or send a letter to Creative Commons, 171 Second Street, Suite 300, San Francisco, California, 94105, USA. The slides in this presentation were originally created by Marc C. Perkins (http://faculty.orangecoastcollege.edu/mperkins). You are free to use, modify, and distribute these slides according to the terms of the Creative Commons license (e.g., you must attribute the slides, no commercial uses are allowed, and future distributions must be licensed under a similar license). Attribution should be given to Marc C. Perkins (and any later editors), including a link back to Marc’s current website. This applies both while distributing the slides and during use of the slides; attribution during use can be satisfied by, for instance, placing small text on at least one of the slides that has been shown (see below for an example). Slides in this presentation based on those created by Marc C. Perkins. http://faculty.orangecoastcollege.edu/mperkins

18. History August 2007: Marc Perkins released first version. http://faculty.orangecoastcollege.edu/mperkins (If you modify these slides and redistribute them, add your information to the list)