Lab 1 – Introduction to biological sciences No quiz or worksheet due today.
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Transcript of Lab 1 – Introduction to biological sciences No quiz or worksheet due today.
Lab 1 – Introduction to biological sciences
No quiz or worksheet due today
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.
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
B10.81
Boron
5
5 protons6 neutrons
Bohr model of BoronPeriodic table ccasa by Armtuk http://commons.wikimedia.org/wiki/Image:Periodic_Table_Armtuk3.svg; Boron art by Marc Perkins
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
B10.81
Boron
5
5 protons6 neutrons
Atomic number
Atomic mass
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 protons11 electrons
11 protons10 electrons
17 protons17 electrons
17 protons18 electrons
Chlorine atom (Cl)Sodium atom (Na)
Chlorine atom (Cl-)Sodium atom (Na+)
The periodic table
Periodic table ccasa by Armtuk http://commons.wikimedia.org/wiki/Image:Periodic_Table_Armtuk3.svg; Boron art by Marc Perkins
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
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 Basic
Highly Acidic
Few protons (H+)
pH Scale ccasa by Slower http://commons.wikimedia.org/wiki/Image:PH_scale.png
Acid Base
HCl
ClH
NaOH
OHNa
(hydrochloric acid) (sodium hydroxide / lye)
pH Scale ccasa by Slower http://commons.wikimedia.org/wiki/Image:PH_scale.png
pH’s of common
items
Lots of protons (H+)
Highly Basic
Highly Acidic
Few protons (H+)
Buffers
• Chemicals that maintain a constant pH in a solution, even when acid or base is added
• Example: Bicarbonate (NaHCO3)
– In solution dissociates into Na+ and (HCO3)-
2333222 COHHCOHCOHOHCO
3HCO
332 HCOHCOH 233 COHHCO
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)
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
Measuring volume
• Use the pipettes, graduated cylinders, or the scale– 1 ml H2O = 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
The periodic table
Periodic table ccasa by Armtuk http://commons.wikimedia.org/wiki/Image:Periodic_Table_Armtuk3.svg; Boron art by Marc Perkins
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
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/
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
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)