SciHawks

AP Chem - took our unit test on Moles and Stoichiometry I.
As you saw, the questions involved one or more of the permutations of the problems done in class and/or the hw.

Bio - we finished our discussion of the factors that can affect the rate of enzyme activity by focusing on the effect of varying the concentration of substrate for a given enzyme concentration, as well as varying the concentration of enzyme for a given substrate concentration.
In 10/11, we finished up work on the complex molecule synthesis model lab.

AP Chem - as we get into our solution stoichiometry unit, we need to know more reaction types, so we went through formula and net ionic equation writing for the two types of double replacement reactions.
We then did the same for the four classic "gas-forming" (CO2, SO2, H2S, and NH3) reactions.

Tomorrow is the Unit 2 exam on moles and stoichiometry I; check yesterday's entry for the list of question types.

Bio - we continued our focus on the factors that affect enzymes/biological protein catalysts.
We learned the meaning of pH - how it indicates the level of acidity or basicity of a solution.
We saw that having too low OR too high a concentration of H+ ions in solution causes reactions with the amino acids in a protein, which then causes denaturing of the protein.
Each protein has an optimal or best pH at which it maintains its proper functional shape by having the ideal amount of interaction between the H+ ions and its amino acid sidegroups.
In 7/8, we also looked at the effect of varying enzyme and substrate concentrations; we then continued our biochemistry model lab.

AP Chem - here is a list of questions by topic that will be covered on your moles and stoichiometry I exam:
1. Determining the percent abundance of two known isotopes of an element, given their isotope masses, and the atomic mass of the element (or getting the atomic mass of an element from the given isotope masses and their percent abundances).
2. Converting any size sample of any substance from grams to moles to number of particles or, for an ideally behaving gas, converting from volume to moles or vice-versa at a given temperature and pressure (the value of R is in the reference tables) ...i.e. using the AP Magic Triangle.

3. Determining the percent composition by mass of the elements in any compound or of water in a hydrate.

4. Using the information in 3. to determine the mass of a given element in a given size/mass of a sample of a compound or to determine the remaining mass of an anhydrate or the mass of water that would be lost from a given mass sample of a hydrate.
5. Determining the empirical formula of a compound or the formula of a hydrate from percent composition data or from raw mass data.

6. Determining the atomic mass of an unknown element in a compound via gravimetric analysis.
7. Determining the empirical formula of a compound via combustion analysis.
8. Determining the molecular formula of a compound given it molar mass , and its previously determined empirical formula.
9. Balancing a chemical equation, and using that equation and given masses of reactants to determine the limiting reactant, and masses of each product, and the mass of excess reactant that remains after the reaction has gone to completion.
10. Given an actual product yield, using the information in 9. to determine the percent yield of the product.
For this exam, I will leave off equation writing i.e. double replacement with precipitation predictions, as well as law of multiple proportion calculations.
STUDY WELL - that means doing MANY problems without EVER leaving out a UNIT or the SUBSTANCE to which the UNIT refers!!! Do not miss this test on Wednesday.

Bio - we reviewed the four major organic biological molecules: carbohydrates, lipids, proteins, and nucleic acids. We then focused on proteins, which have the greatest variety of structures and "jobs"/functions due to the fact that they are made up of up to 20 different amino acids in specific sequences that are between 50 to over 1000 amino acids long!We focused on the effect of temperature on an enzyme: at low temperatures, the enzyme retains its natural 3-D shape so that it can speed up the reaction of the substrate molecule(s) when it collides with and binds them; at low temperatures, though, this collision rate is low so the overall enzyme activity rate is low.
We saw the similarities and differences among the 20 amino acids and noted that the "side chains" of the amino acids cause the protein to "fold" or morph into a particular shape. A protein's specific shape gives it a specific function.
we discussed the various functions of proteins: enzymes speed up the rate of reactions by positioning substrate molecules properly for bond breakage (hydrolysis) or formation (synthesis),

transport proteins carry needed molecules or even wastes to other parts of the body, hormones help signal "target cells" to regulate the various other life functions in the body, antibodies are the main proteins of the immune/defense response of the body; antibodies bind to foreign organisms' surface proteins and immobilize/mark for death the pathogen, motor proteins are capable of sliding over each other causing muscle contraction and other motions.
We then focused on enzymes, showing that they work to hydrolyze or synthesize particular substrates based on the specific complementary shape of the substrate and enzyme.

We then noted that proteins can only maintain their ideal shape in environments of a particular acidity; otherwise, the amino acid chain unravels/"denatures" and the protein loses its shape and can no longer function.
As temperature increases, both enzyme and substrate molecules move faster and collide more frequently so the rate of enzyme activity increases.
However, beyond a given enzyme's optimum/optimal temperature, the enzyme moves too fast and collides with even greater forces causing it to unravel/denature and lose its shape and its active site.

AP Chem - we formally introduced stoichiometry, examining the meaning of balanced equations, and showing how to use the ratios of moles in these equations.
We also noted that the coefficients in balanced equations NEVER indicate mass ratios, only mole, molecule, or formula unit ratios!
We then did a problem in which we determined the quantities of reactants and products consumed and formed, respectively, in terms of moles and then mass.
We discussed the concept of "limiting reactant/reagent", and stressed the crucial importance of using a BALANCED equation in order to determine the limiting and excess reactants.
The limiting reactant limits the quantity of product formed.
We also introduced the computation of "percent yield" of products, and showed how the products shown in a given reaction are not always the exclusive products formed (due to many "side reactions").

AP Chem- we did a qualitative analysis of four unlabeled salt solutions; using our knowledge of solubility rules and precipitation reactions, we can deduce the identity of each unlabeled solution, given a list of four possible salts.
There was a contamination from iron III ions in the tap-water used to make the solutions, a good lesson on the general requirement of using distilled, deionized water for making solutions!
We will continue this analysis on Monday.
We finished our discussion of gravimetric analysis of an unknown element or polyatomic ion; we then did a combustion analysis problem - this type of analysis is more commonly and practically performed on compounds due to the relative ease of burning substances with oxygen.

Bio - we continued our discussion of the structures and some functions of carbohydrates and lipids; we then showed an incredibly diverse and functionally important biological class of molecule: proteins.
For each major class of molecule, we showed the simple building blocks, and the complete complex molecule formed via dehydration synthesis. These complex molecules can be broken down/digested/hydrolyzed via hydrolysis.
In 10/11, we did a carbohydrate, protein, and lipid model lab.

AP Chem - we did another gravimetric analysis problem, using the percent compsition method. We simply write a conservation of mass equation for the element or ion of interest of the reactant and product compound, and then set up the equation for those two masses by multiplying the percent composition of the element or ion of interest times the sample mass. That is one equation with one unknown, which can be solved with a Ti-83,84, 89, or by using graphical methods with your calculator.

Bio - we reviewed our first unit exam, emphasizing the instructions, test-taking skills, mnemonics, and other advice that I gave each of you BEFORE the exam. Those who followed the advice, studied, practiced, and reinforced the methods as we had done in class, naturally did very well. Those who did not listen or could not be bothered to improve their skills as directed, lost many points due to carelessness, insufficiency, or just ignoring the requisite information; of course, we can always learn from these mistakes and get on board with becoming better students.
In 7/8, we looked at the elements and stuctures of carbohydrates, and how to synthesize a complex carbohydrate (polysaccharide) from a simple carbohydrate (monosaccharide) via "dehydration" synthesis i.e. this process also releases/produces water, thus the "dehydration" term.
We also looked at the reverse process of breaking apart (lysing) a complex molecule into simpler building blocks by adding water i.e. HYDROlysis.

AP Chem - we reviewed the percent composition to empirical formula to molecular formula problem, explaining the rationale for each step.
We then did a similar problem involving a three-element compound, and also a percent composition to empirical formula of a hydrated salt problem.

We then tried the most involved problem so far: the gravimetric analysis of a compound via precipitation in which we determined the identity of an unknown cation.

Bio - we began our unit on Biochemistry, the structure and function of the major types of compounds that make up all of the different structures in an organism.
We looked at the general classification of inorganic compounds (do NOT contain BOTH C and H) and organic compounds (contain BOTH C and H).
Water, oxygen, and carbon dioxide are three major inorganic molecules in biochemical reactions.
We introduced the four major types of biological organic molecules: carbohydrates, lipids, proteins, and nucleic acids.

AP Chem - now that we have established how to get the percent composition (mass) of each element in any known compound from its formula, we now worked out how to go from the percent composition by mass of the elements in any compound to that compound's EMPIRICAL formula. We saw that many molecular formulas with common subscript multiples will have the same percent composition, so we also need mass spec. data in order to get the molecular formula, by calculating the "scaling factor".

Bio - took our first unit exam today. Multiple choice average was 20 out of 23, which is good.
In 7/8, we discussed how to make measurements of cells/specimen diameters, using our field of view measurements.

AP Chem - we learned the all-important, quick and easy, AP magic triangle that relates moles of any substance to its mass and number of particles or, if it is an ideally behaving gas, its volume.
We then did GFM and percent composition calculations for molecules, salts, and hydrates.
For hydrates, we learned how to get the mass of water that can be vaporized from any sample of a hydrate, and also the remaining mass of anhydrous salt.
Check out Edline, read the equation writing worksheet, and do that for homework.
There is also a unit study guide for practice with the problems that we have done so far in this unit.

Bio - we reviewed for Monday's exam. The hw answers have been posted on Edline so that you can check the quality of your hw answers, and study for the exam.
I will post today's notes and other study files on Edline by Sunday.
(updated Sunday) - for supplemental study, read Chapter 1 of your Biology textbook; I have posted answers on Edline to select Chapter 1 questions (located at the end of the chapter), as well as some other worksheets with answer keys!
Extra help every Monday morning at 8ish in Room 308.

AP Chem -we discussed the summer assignment exam stressing the importance of writing quality, detailed answers complete with illustrations or examples or both. For germane, relevant responses, more is better on our tests.
We the discussed the reasoning behind "atomic mass" which is the weighted mass average of natural isotopes of a given element, and how the period table atomic masses have been established via mass spectrometry.

Bio - we learned the parts and functions of the microscope.
We also discussed the various other ways that hypothesis statements could be recognized.
We then did some metric unit measurement conversions.
Finally, we looked at various other biologist tools such as chemical indicators, gel electrophoresis, and ultracentrifuges.

Bio - we covered the "standards/conventions" of measurement: any recorded measurement must be to one smaller decimal place than those that are physically marked/etched on the instrument. The greater the number of decimal places, the more precise (and way more expensive!) the markings on the instrument. We also saw how to measure volume with a graduated cylinder (from the miniscus; place a white card behind the cylinder so that the miniscus is easy to read at eye level on a flat surface).
In 11th period, we discussed the parts of the microscope, and did most of the microscope lab, which will be continued.

For the HW due on Thursday (tomorrow), since we did not yet complete all of the objectives, you can omit (leave out) the following (but know that we will cover all of the unit objectives by Friday):
For objective # 6, you need to have only TWO ways to state a hypothesis, not THREE.
Objectives 7 through 17 do not have to be submitted.

AP Chem - we discussed the basis of solubility rules as caused by Coulomb's Law, which states that the attractive force between oppositely charged particles (cations and anions OR electrons and protons) is proportional to the PRODUCT of their charges and INVERSELY proportional to the distance (squared) between the particles. Thus, ions that have a +2 or +3 charge (or -2, -3) and are relatively small will have the strongest ionic bonds to all surrounding oppositely charged ions in a lattice, ergo even the multiple ion to dipole attractions that form between multiple water molecules and each ion is INSUFFICIENT to break the ionic bonds in the lattice, hence the salt tends to be insoluble.
For low charge (+1 or -1), large size ions (i.e. the relative distance between large ions in a salt's lattice is larger than the distance between smaller ions), the ionic bonds are relatively weaker so the multiple ion-dipole attractions to the water molecules per ion are SUFFICIENT to outcompete/break the ionic bonds and cause the ions to go from the lattice into aqueous solution. On our edline site, see the video of sodium chloride dissolving.

AP Chem - took the summer assignment exam. I appreciate the obvious effort that you put in to studying for this exam. I will grade the exam over the next few days and then discuss the results. It is important to do well on this exam as it covers the absolute essentials for being able to do problems throughout this course, especially the skill of naming and formula writing.

AP Chem - we continued our discussion of the Bunsen burner, writing the three possible balanced reactions involved i.e. complete combustion or incomplete combustion of methane, and the decomposition of methane.
We then looked at proper lab safety and cleanup of acid or base spills by treatment with a weak basic salt (sodium hydrogen carbonate, baking soda) or a weak acid (ethanoic acid, vinegar), respectively.

On Monday, we have a 60 minute exam on the summer assignment, and the material from this week (see above, and yesterday). I posted a practice test and answer key on Edline. Be sure that your answers are detailed and sufficient on Monday's exam (see my answer key to the practice exam for examples of sufficiently detailed answers).
Correct spelling of all substances is mandatory! For example, many summer assignments handed in contained the mispelled FLOURINE! There is no such thing as FLOUR-anything in chemistry. The most active halogen is FLU-orine as in "fluorine has the FLU!"
Do not make such careless errors on Monday's exam, or you will receive point reductions.

AP Chem - we looked over the complete classification of matter, and saw that a substance is classified and then named according to its bonding nature.
We then explained the basis of four types of physical separation techniques for mixtures of substances.
We "dissected" a Bunsen burner and saw how the various parts allowed for the proper mixing of methane (and detectable mercaptans gases) with oxygen.

AP Chem - we continued discussing questions from the summer assignment; most of the questions were on compound naming. Compound naming is fundamentally based on the type of compound:
molecular compounds (COVALENTLY BONDED NON-METALS...and there are only 11 of them!) use a prefix system. Ionic compounds (either METAL cations with NONMETAL anions or polyatomic ions in lattices) NEVER use a prefix.

Bio - we further discussed the criteria for life vs. non-life, and then we began a lab safety activity.

To a good start....welcome back Jericho students!
Tues-Day 1:

AP Chem - received the course requirement sheet - please have it signed and returned by Thursday; received course textbook, and filled out class info card.
We got right into Summer Assignment review, going over some naming questions.
We will finish that up tomorrow, and have a test on that by Monday.
I forgot to finish my thought on class grading (because I went into a rant, what a surprise), so remind me about that tomorrow, please. Thanks!

Bio - got started with our course requirement sheet and index cards.
Please have your course requirement sheet signed and returned by Thursday.
10/11 had a double so we began our discussion of the first unit focusing on the fundamental differences between living things/organisms , dead or formerly living things, and NON-living things.