SciHawks

AP Chem- we began the Gas Stoichiometry/Gas Laws Unit by learning another gas-forming reaction: acid plus carbonate salt yields carbon dioxide, water, and salt.
We reviewed writing a "formula equation" from which we use our knowledge of strong and weak electrolytes and solubility rules to write the "ionic equation" and then the "net ionic equation".
We used the balanced equation in order to determine the number of MOLES of gaseous CO2 formed. Then we used the key pieces of information for converting moles of ANY ideally behaving gas to its volume; that is we plugged in the number of moles, temperature, and pressure to determine the volume (in liters) of the gas formed. So, in questions involving gaseous reactants or products, data on only 3 of the four variables (P, T, V, and n) need to be provided in order to determine the fourth variable because PV = nRT and "R" is the universal ideal gas constant.
We discussed that the ideal gas law is an equation that is obeyed more accurately when a gas is under conditions that cause it to have negligible intermolecular attractions and negligible individual gas molecule volume compared to the space between the gases i.e. high temperature and low pressure. We rearranged the gas law in order to solve for the molar mass of an unknown gas given its density at a given temperature: GFM (in grams per mole) = (d R T) / P.

Bio 6- we reviewed for Monday's exam, going over questions about DNA and looking at the big picture regarding chromosomes/chromatids, genes/alleles, and nucleotides/base pairs.
Remember, almost every test this year has a "scientific method" question and/or a graphing question so check your past notes and tests for what is required in your answers:
e.g. proper scientific method involves:
1. using large sample sizes to minimize random error
2. large number of trials to ensure/check for consistency of results
3. one and ONLY one "independent" variable that is DIFFERENT in amount between the control and experimental group or groups.
4. members of each group are selected RANDOMLY.
5. in drug or nutrient experiments, an identical looking "placebo" must be given to the control group; a placebo that has NO effect on dependent variable (what you are actually observing/measuring) must be used.

For graphs, each increment/box MUST be the same amount except for possibly the first box, which would then get a "squiggly" line.
The INDE(x)PENDENT variable goes on the x-axis and the dependent variable goes on the y-axis. DON'T forget to write the units on the LABEL/VARIABLE for each axis.
Your graph TITLE always comes from your HYPOTHESIS or from what you were measuring!
The title is "The effect OF the "INDEPENDENT VARIABLE"(insert the specific variable name in place of "independent variable") on the "DEPENDENT VARIABLE" (insert the specific variable name in place of "dependent variable") or you may write "The relationship between the "independent variable" and the "dependent variable".

Bio 7/8- we reviewed for Monday's exam, going over questions about DNA and looking at the big picture regarding chromosomes/chromatids, genes/alleles, and nucleotides/base pairs.
Remember, almost every test this year has a "scientific method" question and/or a graphing question so check your past notes and tests for what is required in your answers:
e.g. proper scientific method involves:
1. using large sample sizes to minimize random error
2. large number of trials to ensure/check for consistency of results
3. one and ONLY one "independent" variable that is DIFFERENT in amount between the control and experimental group or groups.
4. members of each group are selected RANDOMLY.
5. in drug or nutrient experiments, an identical looking "placebo" must be given to the control group; a placebo that has NO effect on dependent variable (what you are actually observing/measuring) must be used.

For graphs, each increment/box MUST be the same amount except for possibly the first box, which would then get a "squiggly" line.
The INDE(x)PENDENT variable goes on the x-axis and the dependent variable goes on the y-axis. DON'T forget to write the units on the LABEL/VARIABLE for each axis.
Your graph TITLE always comes from your HYPOTHESIS or from what you were measuring!
The title is "The effect OF the "INDEPENDENT VARIABLE"(insert the specific variable name in place of "independent variable") on the "DEPENDENT VARIABLE" (insert the specific variable name in place of "dependent variable") or you may write "The relationship between the "independent variable" and the "dependent variable".
We then did a microscopy lab in which we looked at plant and animal tissue in a region of rapidly dividing cells. The cells were stained and "frozen" so that you could see a snapshot of various cells in various phases of the cell cycle.

AP Chem- we took the Unit 3 Moles and Stoichiometry exam, which is one of the harder exams given the amazing variety of applications of the mole. That is the reason for telling you that it is insufficient to just know the concepts or meanings of terms or formulas; you must practice each type of application until you can do each problem type quickly and accurately. That is also one of the reasons for the great time demand of this course; there is never "no homework". Whether you are re-copying and reading the notes or doing practice tests and worksheets, you must regularly/daily reinforce the class material.
Tomorrow, we begin the Gases unit, which starts with stoichiometry by using the ideal gas law; then we focus on the ideal gas law, properties of real gases, and kinetic-molecular theory.

Bio 6/7- we did two pages of review questions on DNA and transport. We then finished our discussion of the cell membrane/indicator part of the state lab.
We began a microscopy lab by observing cells in various phases of mitosis.

Bio 8- we did two pages of review questions on DNA and transport and then drew an analytical picture of a chromosome to distinguish the terms chromatid, gene, allele, nucleic acid, and nucleotide.

AP Chem- we did a comprehensive redox titration stoichiometry problem in which silver metal was oxidized by (excess) nitric acid to form nitrogen monoxide and aqueous silver ions.
I'll try to post some hw problem types but ALL of the test questions have been explicitly covered in our examples in the notes and repetitively reinforced in the practice tests and worksheets.
Study and bring in your "last minute" review questions (the more specific, the better) to extra help tomorrow.

Bio 6- we finished up the part of the unit on types of asexual reproduction by discussing cutting, grafting, and layering. We then focused on two main unit questions:
1. how does unit code for hereditary/genetic information and what is that information translated into (the amino acid SEQUENCE that determines the structure and function of the protein that is coded for by the DNA; the proteins/enzymes then CAUSE an organism's particular characteristics/traits!
2. how do the "daughter cells" compare genetically to the original "parent cell".

Bio 7/8- we finished up the part of the unit on types of asexual reproduction by discussing cutting, grafting, and layering. We then focused on two main unit questions:
1. how does unit code for hereditary/genetic information and what is that information translated into (the amino acid SEQUENCE that determines the structure and function of the protein that is coded for by the DNA; the proteins/enzymes then CAUSE an organism's particular characteristics/traits!
2. how do the "daughter cells" compare genetically to the original "parent cell".

We finished up our state lab and started to work on our review sheets.

AP Chem- we finished our determination of the percent hypochorite ion in bleach data collection/titration.
There were two redox reactions involved in the lab:
1. As you saw, the first reaction occurred between the hypochlorite ion of bleach with the iodide ion from the KI salt to form chloride ion and triiodide ion (-1 charge).
2. You then titrated this triiodide ion with the thiosulfate ion from the buret solution to form iodide ion and "dithionate" ion ( S4O6 2-). To SEE the endpoint/equivalence point of the titration, we used starch solution, which complexes with the I3 - ion to form a blue-black complex. When all of the I3- was reacted with the thiosulfate, there was then no more blue-black complex that could form so the solution went totally colorLESS!

We finished up our double replacement with precipitation/limiting reactant problem by calculating the concentrations of all remaining aqueous ions. Remember: for SPECTATOR IONS, just divide the ORIGINAL/initial number of moles of each ion by the NEW larger volume (due to the mixing of the two reactant solutions!). That gives you the new concentration of each spectator ion. DO NOT USE THE COEFFICIENTS OF THE BALANCED EQUATION. THEY CAN ONLY BE USED TO DETERMINE LIMITING/EXCESS REACTANTS and to determine the moles of each product formed!
These coefficients CHANGE FOR EACH DIFFERENT REACTION so they can NEVER EVER be used to determine molar mass nor can they ever influence the molar mass of a compound.
We then did an acid base neutralization titration/stoichiometry problem in which the empirical formula of an unknown acid via titration by a known base of known molarity.
Remember, the titration neutralization formula is:
# of moles of H+ from the acid = # of moles of OH- from the base
at the equivalence/end point of the titration!

Some of you are not practicing enough. One of the toughest parts of this course is making enough time to do 5 to 10 of EACH and EVERY different problem type so that you are agile, fast, and accurate with the various problem types and their myriad permutations.

Bio 6/7- we reviewed and discussed the three overall purposes of mitosis especially in complex, multi-cellular organisms. We then looked at the final part of our unit: asexual reproduction.
There are FIVE different types of asexual reproduction, ALL of which involve forming genetically identical new cells from the original cells. There is no such thing as male and female in asexual reproduction; there is just one parent cell that is NOT a sex cell.
We saw binary fission that occurs in bacteria, amebas, paramecia, and euglenas. Budding occurs in yeast and hydra. Sporulation in fungi. Regeneration in starfish and planaria. We also discussed THREE types of asexual vegetative propagation, which has the advantage of producing clones of very healthy or delicious plants/veggies/fruits: cutting, grafting, and layering. We almost finished our state osmosis lab discussion and our plant vs. animal cell lab questions.

Bio 8- we reviewed and discussed the three overall purposes of mitosis especially in complex, multi-cellular organisms. We then looked at the final part of our unit: asexual reproduction.
There are FIVE different types of asexual reproduction, ALL of which involve forming genetically identical new cells from the original cells. There is no such thing as male and female in asexual reproduction; there is just one parent cell that is NOT a sex cell.
We saw binary fission that occurs in bacteria, amebas, paramecia, and euglenas. Budding occurs in yeast and hydra. Sporulation in fungi. Regeneration in starfish and planaria.

AP Chem: we will finish our hypochorite (bleach) titration tomorrow 3rd Period in ROOM 307!
If you show up there first, I'll know that you did your daily hw reading.
:)
Today, we reviewed all of the material that we have covered in the Ch.3 and Ch.4 moles and stoichiometry unit. We also discussed common errors in these problems and in dilution/molarity problems.
We then finished Friday's limiting reagent solution stoichiometry problem. Some of you are not practicing nearly enough as you are unfamiliar with the meaning of the coefficients in a chemical equation. The ONLY purpose of the coefficient is to tell you the RATIO of MOLES of a given reactant used up to MOLES of another reactant used up OR MOLES of a given product formed. THAT IS ALL!!! NEVER EVER use a coefficient from ANY balance equation to compute a molar mass of an element or a compound. NEVER!
Furthermore, in EVERY stoichiometry problem, the question MUST give you ALL pertinent and useful information. In fact, the data in the question DICTATES how you must solve the problem so LABEL ( M or V or n or grams reactant) the data RIGHT in the question and then, as you have seen, we practically always:
1. convert to ACTUAL moles of substance
2. plug that into the BALANCED equation to determine limiting and excess reactants
3. use the limiting reactant MOLE RATIO to determine ACTUAL moles of product(s) formed and MOLES of other reactant(s) used up.
4. convert MOLES to grams or (given molarity) volumes of any and all substances!
That is it.

Bio 6- we completed our detailed pictures of DNA replication that takes place during the S part of interphase. We related our picture to what is occurring on the chromosome: the DNA replication LITERALLY forms a second identical "sister chromatid" making the chromosome go from a single-chromatid chromosome to a double-chromatid chromosome. Without this important formation of identical sister chromatids, mitosis could NOT occur because the daughter cells would not have the same number and types of chromosomes as the original cell due to the lack of DNA.
We then discussed the importance of the Watson-Crick model/picture of DNA, showing how it explained/accounted for the ability of cells to reproduce identical cells with the same genetic information and also how DNA could code information that is translated into the specific amino acid sequence of all of the proteins that give an organism its specific traits and characteristics.
We began a DNA and mitosis worksheet that we will finish tomorrow.

Bio 7/8- Bio 6- we completed our detailed pictures of DNA replication that takes place during the S part of interphase. We related our picture to what is occurring on the chromosome: the DNA replication LITERALLY forms a second identical "sister chromatid" making the chromosome go from a single-chromatid chromosome to a double-chromatid chromosome. Without this important formation of identical sister chromatids, mitosis could NOT occur because the daughter cells would not have the same number and types of chromosomes as the original cell due to the lack of DNA.
We then discussed the importance of the Watson-Crick model/picture of DNA, showing how it explained/accounted for the ability of cells to reproduce identical cells with the same genetic information and also how DNA could code information that is translated into the specific amino acid sequence of all of the proteins that give an organism its specific traits and characteristics.
We almost completed our lab discussion on the NY State osmosis lab; we will do so on Wednesday before we begin our next lab.

AP Chem- I have posted a plethora of practice tests complete with detailed answers. If you do these tests and understand the methods and answers, Thursdays test will be a breeze for you. So that you have time to do these practice tests and peruse the notes and study guide, I am only assigning a few Ch. 4 text questions to be handed in next Tuesday (along with the one or two questions from Ch.3, if you did not complete them all previously).
Chapter 4 HW questions: 16, 24, 30, 36, 42, 54, 58, 62, 64
We finished the double-replacement (ALL double replacements are NON-redox reactions so do NOT bother with the half-reaction method for them) stoichiometry problem in which we determine the volume of acid required to completely react with the sulfide salt. ALL acid + sulfide salt reactions produce gaseous dihydrogen sulfide gas!
We then did a redox titration stoichiometry problem totally from scratch, just using the NAMES of the reactants and products and balancing the reaction by using the half-reaction method. We identified the oxidizer and the reducing agent and then we applied the MOLE RATIOS from the BALANCED equation (as we will always do). From the data, we determined the percentage of iron (as 2+ ions) in a sample of iron ore.
We then began another double replacement (with precipitation) problem from scratch, which we will develop further on Monday. In this problem, we will focus on the mass of precipitate formed as well as the concentrations of all dissolved ions that remain in solution.

We continued our lab prep for the titration of the hypochlorite ion in bleach. You learned how to condition a buret so that the titrant is not diluted by water droplets that may have been inside the buret. You weighed out potassium iodide, which will form a complex with starch to be used as an indicator for the redox reaction. Some of you did not label (as instructed) your weighing dishes so you will have to start that part again.

Bio 6/7- we further discussed and labelled the structure/components of DNA. We have begun to see/draw out the mechanism by which a DNA molecule can replicate into two exact copies of the original molecule.
We further discussed the required State Lab on osmosis and diffusion through a cell membrane; we used the results of the indicator tests to make deductions and conclusions regarding which substances diffused through the cellulose membrane that we made.

Bio 8-we further discussed and labelled the structure/components of DNA. We have begun to see/draw out the mechanism by which a DNA molecule can replicate into two exact copies of the original molecule.

AP Chem: we did a redox titration problem in which we:
1. wrote the formulas of the reactant and product particles (from their names)
2. used the half-reaction method in order to balance the equation
3. use the volumetric data AND the balanced equation to determine the number of moles of each reactant used up at the equivalence point.
4. converted moles to grams for the reactant of interest (H2O2)
5. calculated the mass percent (part/whole) x 100% of the H2O2 in the solution

We also identified the oxidizing AGENT (which, itself, got reduced) and the reducing AGENT (which, itself, got oxidized) in the reaction.
We started another solution stoichiometry problem, a double replacement between zinc sulfide and hydrochloric acid.


Bio 6 – we discussed the important overall results of mitosis/cytokinesis. We then discussed cancer, uncontrolled cell division, and how cancer cells harm an organism by using up most of its needed nutrients thus depriving normal cells of nutrients/sources of energy.
We began to discuss the composition and structure of DNA from which we will see how chromosomes can be identically replicated so that cells can be identically replicated (during mitosis and cytokinesis).
Tomorrow, I will briefly review the main errors from your cell test and address other questions that you may have.

Bio 7/8- we reviewed the phases of mitosis and related them to the photographs of the cells in these various phases of mitosis. We then discussed the important overall results of mitosis/cytokinesis. We discussed cancer, uncontrolled cell division, and how cancer cells harm an organism by using up most of its needed nutrients thus depriving normal cells of nutrients/sources of energy.
We began to discuss the composition and structure of DNA from which we will see how chromosomes can be identically replicated so that cells can be identically replicated (during mitosis and cytokinesis).
Tomorrow, I will briefly review the main errors from your cell test and address other questions that you may have.

AP Chem- we finished the "percent yield" problem and discussed the meaning of high yield vs. poor yield in a given chemical (usually organic) reaction pathway/mechanism. Conditions that lead to a larger number of "side or alternate reactions" will produce a lower yield of the desired product.

We then reviewed the unit for solutions: Molarity.
We saw the four parts of the equation and via algebraic rearrangement, showed how to solve for the required grams of reactant to make a solution of known molar concentration and volume.
We then discussed the basis and meaning of the "dilution formula", ViMi = VfMf , which shows that moles/grams of dissolved solute do not change when solvent is added!

We then did a solution stoichiometry problem (acid-base neutralization) both with and without a limiting reactant.

Bio 6/7- we performed the other part of the NY State Lab on cell transport/diffusion.
We will finish the writeup discussion on that lab on Friday.
We then revisited mitosis/cytokinesis as we started to focus on some of the end results of the mitosis and cell division process.

Bio 8- we reviewed the reasons for cell division (divide or die) and then discussed and viewed images of the phases of mitosis and cytokinesis.
The 5 phases can be remembered by using the mnemonic: IPMAT.
We noted the changes that occur during each phase of mitosis and saw how to relate the picture of a dividing cell to its particular phase in mitosis.

AP Chem- we discussed the meaning of balanced chemical equations with which we can determine the limiting and excess reactants given actual (mass or mole) quantities of said reactants.
Balance chemical equations only and ever give MOLE ratios or reactants and products, NEVER mass ratios of reactants and products.
For example, from the balanced equation, 2 moles of H2 react with 1 mole of O2 to form 2 moles of H2O. This CANNOT mean that 2 grams of H2 react with 1 gram of O2 to form 2 grams of H2O due to the great difference in molecular masses of H2 and O2. In fact, as you can see and measure, 4.032 g of H2 reacts per 32.0 grams of O2 to form 36.032 grams of water, which is not a 2 to 1 to 2 mass ratio.
We then did a problem in which we converted grams of each reactant to moles of each reactant, plugged those molar quantities right into the balanced equation to see which reactant had the lowest mole ratio; this reactant is the limiting reactant, which we use to determine the theoretical maximum number of moles or grams of each product formed. We then determine the quantity of UNreacted/left over excess reactant.
Given ACTUAL experimental quantities of products (called the "yield"), one can determine the "percent yield" for a given particular experiment i.e. if 120.00 g of product A were predicted from the limiting reactant and balanced equation BUT only 90.00 g of product A were formed (due to side reactions, etc.), the percent yield for that particular experiment is 90.00/120.00 or 75.00%.
Your hydrate lab is due tomorrow; we will start a new stoichiometry lab tomorrow, also.

Bio 6- by using actual electron microscope photographs of cells in various phases of mitosis and cytokinesis, we clarified and reviewed the steps involved in cell division.
We then discussed one of the differences in plant vs. animal cell division: animal cells undergo cytokinesis by "pinching in" the cell membrane (forming a "cleavage furrow") until there are two separate cells; plants form separate cells by forming a "cell plate" that forms a new cell wall and membrane between the two separate cells.

Bio 7/8- we finished the onion cell osmosis and "cell membrane" transport/use of indicators lab.
We will continue with mitosis and cytokinesis tomorrow.

AP Chem- we labelled/named some of the reactions that we had balanced: double replacement with precipitation, acid-base neutralization, etc.
We saw that, when a redox reaction occurs (especially in aqueous solutions), simple mass balancing of reactants and products is inadequate to obey the Law of Conservation of Charge.
We then developed the "Half-Reaction" method for balancing a redox reaction; last year, you learned the "oxidation number" method for balancing a redox reaction. The "half-reaction" method is easier in that it avoids the use of an arbitrary oxidation number system and deals solely with masses and charges.
We practiced a few examples, two redox reactions in acidic solutions (excess H+) and one in basic solution (excess OH- ... TWO MORE STEPS).
We then introduced the concept of "limiting" reactants and "excess" reactants in stoichiometry.
With a balanced equation and known quantities of reactants, you can determine which of the reactants LIMITS the number of moles of product(s) formed.
We discussed our hydrate lab and came up with two plausible UNAVOIDABLE experimental sources of "error"/uncertainty.
For excess water loss from the hydrate, if some minor anhydrous salt sublimation occurred (unbeknownst to you of course, you CANNOT see this occurring!), the mass lost would be recorded as water mass lost, thus increasing the perceived percent water in the original hydrate.
If the anhydrous salt somewhat rehydrated from moisture in the air (during cooling...again, you cannot see this occurring), the mass lost would be LESS than it would have been if NO water remained, thus decreasing the perceived percent water in the original hydrate.
Your job in the writeup is to plug in data that is consistent with each of these two scenarios and show your calculation for the percent water (as instructed). I do not care what the numbers are as long as they are consistent with the scenario and with you original hydrate mass.

Bio 6/7- we began our new unit on mitosis/cell division/DNA by discussing the reason/necessity for cell division. We focused on the increase in both surface area and volume as a cell grows. However, for any growing cell, the volume increases faster than the surface area so the cell must divide or die due to the lack of timely diffusion of nutrients to their required locations in the cell.
We went through the phases of mitosis with cytokinesis, including the "rest phase", interphase, during which the cell and its parts grow and during which the DNA replicates itself.
We began the state lab on diffusion in an onion cell.

Bio 8- we began our new unit on mitosis/cell division/DNA by discussing the reason/necessity for cell division. We focused on the increase in both surface area and volume as a cell grows. However, for any growing cell, the volume increases faster than the surface area so the cell must divide or die due to the lack of timely diffusion of nutrients to their required locations in the cell.

AP Chem- here are the Chapter 3 HW problems that will be due next Thursday:
#'s 25, 26, 30, 42, 48, 56, 68, 70, 78, 82, 110 , 126 (we have done each of these problem types in the notes, so far)...
also #'s 90, 99, 106 (you will be able to do these for sure by next week)

Your hydrate lab writeup will be due by next Wednesday. Make sure that you show all work explicitly and that you highlight the TWO hydrate prediction calculations that you did for your lab group.

Today, we did another gravimetric analysis problem in which we used mass (gravimetric) data to deduce the gram atomic mass of an element. The problem involved about six steps so this was relatively difficult and should require practice and repetition for hw (see practice test, etc. files on Blackboard). We then did simple (non-redox) equation balancing review; balanced equations show the MOLE RATIOS (NEVER gram or mass ratios!) of the reactants and products.

Bio 6/7- took the Cells and Cellular Transport Unit exam; then we finished our Plant and Animal Cell lab discussion after which we began the first of this year's four NY State Regents labs.

Bio 8- took the Cells and Cellular Transport Unit exam.

AP Chem- we solved the conundrum from yesterday's combustion analysis problem; why did our empirical formula have crazy numbers? Because the total mass of carbon and hydrogen (from the carbon dioxide and water, respectively) did not add up to the mass of the original unknown compound i.e. the law of conservation of mass was not observed. That told us that there MUST be another element in the original compound; that compound must be oxygen because that is the only other element in the products!
We then solved, by subtraction, for the mass of O in the unknown, converted to moles, got the simplest whole number mole ratios, which led us to the empirical formula of para-cresol: C7H8O.
We used the molecular mass to get the scaling factor, with which we determined the molecular formula. The scaling factor was an INTEGER so we knew that the empirical formula was correct.
We then discussed a bit of organic naming on benzene type rings: ortho, meta, para, with which we deduced the structural formula of the alcohol- no wonder that its an herbicide.
We re-started our hydrate lab during which we used the percent composition of prospective/possible hydrates of copper II sulfate in order to judge when the "constant mass" heating was likely over.
I'll return your exams tomorrow and we'll try to do a lot before this weekend so that you can make a big dent in the practice tests on Blackboard.

Bio 6/7- tomorrow we have our unit exam on Cells and forms of Cell Transport. There are lots of links, videos, practice sheets with answer keys for you to reinforce your knowledge.
Looking forward to an even more successful outcome on this unit; make sure that you use the test-taking skills that you have learned so far this year- they can ONLY help your score.

We finished our final cell objectives on cells, showing how and why they work together to maintain homeostasis in a cell to keep it alive.
We finished our plant and animal cell; for reinforcement, we added an activity in which we could see the results of osmosis when the plant cells are placed in a hypotonic and a hypertonic solution.

Bio 8- tomorrow we have our unit exam on Cells and forms of Cell Transport. There are lots of links, videos, practice sheets with answer keys for you to reinforce your knowledge.
Looking forward to an even more successful outcome on this unit; make sure that you use the test-taking skills that you have learned so far this year- they can ONLY help your score.
We finished our final cell objectives on cells, showing how and why they work together to maintain homeostasis in a cell to keep it alive.

AP Chem- we started to get to the powerful and practical parts of this unit. We did a multi-part problem in which we went from percent composition to empirical formula to molecular formula. We saw how to calculate a "scaling factor" in order to know by which INTEGER to multiply the subscripts in the empirical formula to get the molecular formula. If the scaling factor as calculated turns out NOT to be a whole number, then the empirical formula that you are using MUST be WRONG, so you must correct whatever errors that led to that incorrect empirical formula mass.
We then described the technique of combustion analysis and began a problem in which we deduced the empirical formula of a compound from the masses of CO2 and H2O produced from a given mass of the unknown.

Bio 6- we drew out and explained in detail the effect of placing cells in hypotonic, isotonic, or hypertonic solutions.
We categorized and gave examples of various types of passive and active transport.
We then discussed the various levels of organization in complex organisms.

Bio 7/8 - we drew out and explained in detail the effect of placing cells in hypotonic, isotonic, or hypertonic solutions.
We categorized and gave examples of various types of passive and active transport.
We then discussed the various levels of organization in complex organisms.
We finished out Plant and Animal Cell lab; then we added an activity to that lab to see the effect of hypertonic saltwater solution on the Elodea plant cells; we noted that the cells shriveled due to osmosis of water out of the cell to the region of lower water concentration (the hypertonic solution).

AP Chem- we did some more "molar mass" calculations of salts and hydrates. We calculated the % water in a hydrated salt and then did the percent composition to empirical formula calculation, explaining the logic of choosing a 100. g sample and then seeing that we are trying to get the mole ratio of atoms (or ions) in a given compound. The important lesson that you will NOT SEE in any text is how much you can "round up or down" in these particular problems. We also drilled decimal to fraction to multipliers so that you know what to do when you solve for empirical formula and you initially do NOT get a nice whole number ratio.
We began our lab on % composition of a hydrate, a gravimetric analysis with which we will determine its empirical formula.

Bio 6/7- we did examples of passive transport, particularly "facilitated diffusion", which is regular diffusion but with the "help" of a transport protein channel; no net energy input is needed for this process, of course.
We contrasted that with an example/illustration of "active transport", which is an energy REQUIRING process; the energy is supplied by using up ATP molecules for the energy stored in their bonds.
We then finished our plant and animal cell lab.

Bio 8- we did examples of passive transport, particularly "facilitated diffusion", which is regular diffusion but with the "help" of a transport protein channel; no net energy input is needed for this process, of course.
We contrasted that with an example/illustration of "active transport", which is an energy REQUIRING process; the energy is supplied by using up ATP molecules for the energy stored in their bonds.

Here are the objectives that we have not yet finished discussing in class; you will not be graded on the following:

Why is it essential that a cell’s organelles work together?

Describe three examples of how two or more organelles work together to maintain cellular homeostasis.

What types of organisms have specialized cells?

How does a single-celled organism carry out all life processes?

Name two common single-celled organisms and a feature of each associated with a specific life function.

What phenomena with respect to diffusion were observed during the NY State Regents lab on the “onion cell”?

What happens to a plant cell or any cell placed in a hypertonic solution? An isotonic solution? A hypotonic solution?

Why does the above occur?

What are the levels of organization in complex, multi-cellular organisms?

You are responsible for all of the other objectives, which will be graded.

AP Chem- NOTE: because there is no school on Monday, I will have extra help on Tuesday morning from about 8AM to 8:45 AM.
We launched write into the Moles/Stoichiometry unit. We started with a review of (weighted average) atomic mass and then went on to the AP version of the "Magic Triangle", with which we can easily inter-convert moles, grams, liters (under ANY T and P conditions!), and particles.
We then did a percent (by mass) composition example.
I have posted some files for you to acquire some more experience with this unit.

Grading the Quantum/Periodicity exam: most of you followed the advice of providing drawings/illustrations (with reference to said drawing) as part of your explanations and, by doing so, more easily earned your credit. I am very impressed with the logic and writing ability of most of the class. However, there is a small minority of students who did not learn the super-important lesson (that I discussed with you in class i.e. WHY the photoelectric effect occurs) from the last exam: an EXPLANATION questions requires that you answer HOW and/or WHY something occurs by linking facts together in a logical sequence to lead to the conclusion that is asked about in the question. Merely re-stating WHAT occurs is called a DESCRIPTION; descriptions do NOT answer explanation questions. If your answer to a HOW/WHY question only states WHAT occurred (especially when "what occurred" is already IN THE QUESTION), credit CANNOT be awarded on the AP exam or on our tests. Drawing out what occurs can BEGIN to lead you to how and why something occurs. Do not forget this important distinction; if you need more practice on seeing the difference between a description and an explanation, see me at extra help.

Bio 6- NOTE: I just properly linked my gradebook to your Blackboard account so you should be able to see your currently graded test, hw, and (by Tuesday!) lab grades. Sorry I forgot about that on Tuesday.
ALSO NOTE: because there is no school on Monday, I will have extra help on Tuesday morning from about 8AM to 8:45 AM.
Today, we introduced the very important life process of cell transport on the molecular level; we defined the term, "diffusion"; then, we saw and explained the CAUSE of diffusion- diffusion MUST occur in any gaseous, liquid, or soluble aqueous solution DUE TO the RANDOM (just as likely in ANY direction) movement of particles/molecules/ions/atoms.
We saw that diffusion occurs through a selectively permeable membrane only to those substances that can fit through the membrane or its "facilitator" channels/proteins.

Bio 7/8- NOTE: because there is no school on Monday, I will have extra help on Tuesday morning from about 8AM to 8:45 AM.
Today, we introduced the very important life process of cell transport on the molecular level; we defined the term, "diffusion"; then, we saw and explained the CAUSE of diffusion- diffusion MUST occur in any gaseous, liquid, or soluble aqueous solution DUE TO the RANDOM (just as likely in ANY direction) movement of particles/molecules/ions/atoms. We saw that diffusion occurs through a selectively permeable membrane only to those substances that can fit through the membrane or its "facilitator" channels/proteins.

AP Chem- today you all got a true taste of the college experience although college science exams often last up to three hours! Still, to write detailed explanations for 80 minutes is great experience and will strengthen you as students.
Fortunately (for your writer's-cramped hands), only the bonding and intermolecular attractions unit (which both stem from this unit) approaches the level and number of explanations that you just learned in this unit.
On Friday, we have a single period but we will cover a lot of ground. We will complete all of the problem types in CHAPTER 3 of the text within the next two or three classes. So, read chapter 3, which is MOSTLY review material involving balancing equations, stoichiometry, and moles; these are all topics that you should already have considerable familiarity and facility with.

Bio 6/7- we compared and contrasted plant and animal cells; then we began a lab in which we will see, with the aid of microscopes, some of those differences.

Bio 8- we reviewed our last test and went over some test-taking skills. Then, we compared and contrasted plant and animal cells.

AP Chem- Chapter 7 hw solutions will be posted shortly.
As a time-saver on tomorrow's test, you may want to write out the following ONE TIME (at the beginning of ONE of your relevant explanation answers) to cover your basic CAUSES of any of your explanations:

1. Coulomb's Law states that the greater the quantity of opposite charges, the greater the force of attraction. The greater the quantity of same charges, the greater the force of repulsion.
The law also states that, the FARther the distance between opposite charges, the LESSER the force of attraction. The FARther the distance between same charges, the LESSER the force of repulsion.

2. Zeff is effective nuclear charge: it is the nuclear charge minus the number of shielding/inner Principal Energy Level (PEL) electrons (Zeff = Z-S) . According to Coulomb's Law, the greater the Zeff on an electron, the greater the attraction between the electron and the nucleus.

3. OPEL's: are occupied principal energy levels. Via Coulomb's Law, the greater the number of OPEL's, the FARther away the valence electrons are, therefore, the LESSER the attraction of those electrons to the nucleus.

That should cover the BEGINNING of any explanation. You can then REFER to the above in any explanation answer by writing: "as stated in 1(or 2 or 3)".
Hope this helps and saves you some time.

Bio 6- we finished our discussion of the structure and function of organelles that are common to most eukaryotic cells. We then compared and contrasted simple, small, primitive prokaryotic cells with larger, more complex, eukaryotic cells.

Bio 7/8- we finished our discussion of the structure and function of organelles that are common to most eukaryotic cells. We began to compare prokaryotic and eukaryotic cells.
We must also do the unit 2 test review tomorrow.
We then finished our pH lab discussion and began our new lab on plant and animal cells, which we will finish on Friday.

AP Chem- we reviewed the first ionization anomalies among Group 3A elements and saw that the first IE value is LOWER than expected due to the shielding of the p electron by the two s electrons, making the p electron less attracted to the nucleus thus requiring LESS ENERGY for removal of said p electron.
We saw that Group 6A elements ALSO have anomalous/lower than expected first IE's BUT this is NOT due to s to p shielding; we drew the orbital diagrams to show that the electron pair repulsion, which is more significant between electrons in the same orbital/region of space due to their mutual proximity, causes one of those two electrons to be more easily removed from the atom.

We then explained the trend in SUCCESSIVE ionization energies to see that when the first NON-valence electron is removed, their is a DISPROPORTIONATE increase in ionization energy required. This is because NON-valence electrons are attracted to their nucleus by a much higher Zeff and these electrons are located closer to the nucleus (lower # OPEL's) than are valence electrons. Both of these factors cause greater nuclear to electron attraction.

We then defined "electron affinity" as the energy released when a gaseous atom GAINS an electron. This is measured via a laboratory procedure in which electrons are directed at a gaseous sample of atoms and the energy change is then measured. Atoms that have high EA (electron affinity) do so because of a relatively high Zeff, few OPEL's, AND not too much electron-electron repulsion as a result of gaining the new electron.
Your next test is on Wednesday and will cover all notes/subtopics done in class since the last exam (starting with Schroedinger's quantum number solutions and ending with explanations of all Periodic trends.

Bio 6/7- we continued to describe the structure and function of eukaryotic cell organelles. We saw a video comparing/contrasting eukaryotic and prokaryotic cells.
We reviewed some test questions and further discussed test-taking skills (identifying and underlining KEY TERMS in the question so that you are FOCUSED on what is actually required in your answer e.g. the pepsin PROTEIN-digesting (not starch/carb-digesting) enzyme question).
We then almost finished our Biochem lab discussion regarding pH.

Bio 8- we continued to describe the structure and function of eukaryotic cell organelles. We saw a video comparing/contrasting eukaryotic and prokaryotic cells.

...kidding, I hope. I'm new to podcasting/vodcasting but I hope that you appreciate the effort.
My first vodcast/tutorial for AP Chem is up on Blackboard; the video sounds like a recording from inside a car engine but I think that this lesson/example on determining quantum numbers for a given principal energy level will be helpful (more than reading a text, anyway).
When you click on the link, the video will load in your browser BUT then you must click on the "play/forward arrow icon" for the video to start. If the video is too small, there is a "full screen" feature at the bottom right corner of the video. You may want to decrease the volume a bit to cut down on the recorded "white noise" (sorry about that). You can also directly download the file to your computer and open the video with any Flash-video playing software.

I'm sure that the quality will increase exponentially as I learn how to produce more stylish flash-files. For now, just focus on the content and the message, which is to improve your AP Chem abilities.

AP Chem- Continue with the Chapter 7 HW questions, all of which you can do except #'s 30, 94, and 110; hand in your work on Monday. Also, peruse (the OPPOSITE of skim) the class handout on the explanations of the periodic trends and let me know if you have any questions about them on Monday. Also on Monday, I'll have you type your password into my online gradebook so that you can confirm/keep track of your grades on Blackboard
We continued our comparison and explanation of atomic sizes among isoelectronic species (atoms or ions) in terms of (1) Zeff , (2), # of OPEL's, (3) and electron-electron repulsion in the valence shell.
We then used those same factors to explain the Periodic Trends in First Ionization Energy.
We saw that metallic elements have low Zeff on their valence electron(s) and thus have low first IE and that nonmetallic elements have relatively high Zeff on their valence electron(s) and thus have higher first IE's.
We then used ORBITAL DIAGRAMS from the Quantum Model of the atom to explain ANOMALIES in the first IE trend. We invoked the concept of "shielding" WITHIN a principal energy level: the fact that "s" electrons are, on avg., closer to the nucleus than are "p" electrons so that the s electrons partially shield or BLOCK some of the positive nuclear charge from the p electrons thus making the p electrons easier to remove from the atom (lower than PREDICTED first IE!).
Continue with the Chapter 7 HW questions, all of which you can do except #'s 30, 94, and 110; hand in your work on Monday.

Bio 6- we described the structure and life function of the following cell organelles:
the cell membrane (regulation, transport), the cell wall (in plant and bacterial cells only), which just provides a supportive, protective framework for the cell membrane, the cytoplasm (the medium in which most metabolic activities/reactions occur and the nucleus (regulation, reproduction).
I'll attempt to post some of your grades (not the labs) on your password protected Blackboard account.

Bio 7/8- we described the structure and life function of the following cell organelles:
the cell membrane (regulation, transport) and the cell wall (in plant and bacterial cells only), which just provides a supportive, protective framework for the cell membrane.
I'll attempt to post some of your grades (not the labs) on your password protected Blackboard account.

AP Chem- Today, for most of you, was your introduction to truly UNDERSTANDING chemistry; it can actually make sense now!
We began the logical explanation of ALL atomic periodic trends and most chemical phenomena by defining and applying THREE FACTORS that all stem from COULOMB'S LAW.
Coulomb's Law states that electrostatic force between two particles is proportional to the quantity of charge on each particle and INVERSELY proportional to the SQUARE of the distance between the two particles. In English, the more highly charged the ion or number of protons, the greater the electrostatic force from them and, the greater the distance between two charged particles, the LESSER the electrostatic force between them.
We applied this law to explain how increasing Zeff (effective nuclear charge, Z-S) causes a greater attraction on an electron and how an increasing number of OPEL's (OCCUPIED-by electrons-principal energy levels) will increase distance of valence electrons from the nucleus and thus decrease nuclear attraction on these electrons. We also saw that electron-electron repulsion within a given PEL/shell can cause electrons to "spread out" and increase the size of an anion.

We explained the trends in atomic radius across a period (from left to right) and down a group; we even explained the LACK of change in atomic radius across the transition metals part of a period.
We explained the trend in ionic radius for metals: ALL metal cations are SMALLER than their "parent" atoms and ALL nonmetal ANIONS are LARGER than their "parent" atoms.
We defined the term "isoelectronic" and saw how to compare the sizes of isoelectronic particles.
Tomorrow, I have to very briefly talk about the "Heisenberg Uncertainty Principle", which is philosophically astounding, because I forgot to describe it on Friday. Remind me if you can, thanks!

Bio 6/7- we introduced our new unit on Cells and Cell Processes. We discussed the basic unit of all living things and also the difference between a live and dead organism at most fundamental molecular level! Living things are vast collections of ORGANIZED organic and inorganic molecules! Dead things have a less coordinated and organized collection of these molecules. Non-living things, no matter how organized, are NOT made up of the molecules organized as CELLS!
We then continued to work on our lab write-ups.

Bio 8- we introduced our new unit on Cells and Cell Processes. We discussed the basic unit of all living things and also the difference between a live and dead organism at most fundamental molecular level! Living things are vast collections of ORGANIZED organic and inorganic molecules! Dead things have a less coordinated and organized collection of these molecules. Non-living things, no matter how organized, are NOT made up of the molecules organized as CELLS!