SciHawks

Physics- finished the spring constant lab, and then went over common Regents spring-constant questions.
We reviewed for Wednesday and Thursday's Unit 5 exam.
Be sure to check Blackboard and review the practice tests, and multiple choice explanations from our packet.

This test covers: momentum (sticky, bouncy, and explosion), circular motion (qualitative and quantitative), elevator problems, and spring problems.

AP Chem - began our unit on Bonding; we first did some descriptive chemistry, but now we go further - we can understand the CAUSE(S) of each particular chemical reaction. When you understand these causes, you truly understand chemistry, and can predict the products of tens of thousands of reactions. That knowledge can have great value and power!

Physics - solutions to the Thanksgiving assignment have been posted since noon; solutions to the multiple choice questions from our unit 5 packet will be posted at about 8PM.

In case you did not receive the email, our unit 5 exam will be given on Wednesday (part 1) and Thursday (part 2) of this week!

For reinforcement/practice for this exam, come to extra help tomorrow morning.

We also discussed the "blocks" of elements with respect to the Aufbau principle, as well as some of the physical properties of the elements.

Happy Thanksgiving to all of you and your families!

Physics- did an impulse and an elastic collision momentum problem in the Momentum 4 ditto. We then reviewed the concept of "centripetal force REQUIREMENT", which is equal to the square of an objects velocity divided by the radius of its circular path. The SOURCE or sources of the centripetal force must add up to the centripetal force requirement in order for the object to maintain a circular path/orbit.

We then did several circular motion problems. Most of these problems involve either one or two steps, depending on the given variables.

We then finished (almost) the Hooke's Law spring constant lab in which we determined the direct proportion relationship between the force on a spring and its stretch distance.
The spring constant, k, in Newtons per meter, indicates the elasticity or stiffness of the spring: the greater the k value, the stiffer/less elastic the spring.

Physics - we reviewed circular motion and redefined/revised our view of centripetal force as a REQUIRED FORCE, that is the force that is NEEDED in order to maintain an object's circular orbit.
Recall, sometimes that force is supplied by the tension in a rope attached to the object, sometimes it is the force of friction on the tires of a car travelling in a circle, sometimes it is the object's own weight, the force of gravity on an object.
When the centripetal force requirement is NOT MET, i.e. the object is going too fast so there is not enough force capable of meeting this enormous centripetal force requirement (due to the high speed, Fc= mv^2/r is excessively high), the object will fly off tangent to the path of the circle.

We then did a few circular motion problems, using an algebraic substitution method as well as the usual plugging-in numbers method.
We then did another momentum problem.
Tomorrow, we will finish up the springs lab, as well as some Hooke's Law spring questions, and do as much of the rest of the packet before vacation.
There will be a unit test on the second and third days back from Thanksgiving vacation.

I posted the brief vacation assignment on Blackboard: it is four questions from the unit packet covering a variety of question types from this unit.

We then used the quantum mechanical model of the atom to explain the anomalies in the first ionization energy trend that occurs for elements in group 3A (due to s electrons shielding of the p electron) and in group 6A (due to increase electron electron repulsion in a given valence shell p orbital).

Physics - finished up our spring constant lab - we'll finalize our answers during the next lab session.
We introduced circular motion, emphasizing that an object moving in a circle is ALWAYS accelerating towards the CENTER of the circle (its centripetal acceleration) and this acceleration is caused by some force (due to friction, gravity, tension in a rope, or some other source) that causes centripetal force towards the center of the circle.

We looked at the various formulas involved. We will solve circular motion problems on Monday and Tuesday.

AP Chem - we explained the relative sizes of atoms and their corresponding common stable ions by showing the effects of the three factors that cause all periodic trends and chemical phenomena: Zeff on the valence electrons, the number of OPEL's, and the degree of electron-electron repulsion in the valence shell.
We then began to compare the sizes of an isoelectronic series of species.
Be sure to peruse the explanations of ALL periodic trends as written out in the notes posted on Blackboard/handed out in class.

Physics - we did several types of conservation of momentum problems in the Momentum 2 and 3 worksheets in our unit 5 packet.
We combed each problem for the variables and keywords to see whether a question involved the impulse formula, the bouncy/elastic collision formula, the sticky/inelastic collision formula, or the explosion formula.

AP Chem - took the Quantum unit exam.

Physics - we finished an impulse problem in which we needed the frictional force in order to calculate the applied force. We used mu times the normal force to get the frictional force. We realized from our drawing that the frictional force is directed opposite to the applied force, and therefore MUST have the opposite/negative sign.

We then learned the Law of Momentum Conservation: p before = p after has always been observed for all physical phenomena! ALWAYS draw a picture and CAREFULLY make sure that the SIGN of the number is consistent with the DIRECTION of the velocity/momentum!

We applied this equation to three scenarios:

1. Explosions    0.00  (kg m s^-1)   =      m1v1 + m2v2

2. Bouncy/Elastic Collisions between two objects:   m1v1(initial) + m2 v2(initial) = m1v1(final) + m2v2(final)

3. Sticky/Inelastic Collisions between two objects: m1v1(initial) + m2 v2(initial) = (m1 + m2) v(final)

We applied these detailed formulas to three problems, one of each type.

Do problems #2 and #4 in the Momentum 2 packet, and check your answers on Blackboard later!

AP Chem -Tomorrow we have the unit exam on the Quantum Atom:
There will be a set of multiple choice questions on quantum numbers, and the various rules of electron energy order and proper configuration in a ground state atom or ion.
The other questions cover the entire unit notes:
EMR phenomena, Planck, Einstein's explanation of the photoelectric effect
Calculation of bond energies using photons to break the bonds.
the Bohr Model - both quantitative and qualitative (explanation of emission spectra)
the Quantum Mechanical Model of the Atom:
the Aufbau Principle, the Pauli Exclusion Principle, Hund's Rule, energy sublevel ordering,
Quantum numbers: their physical meaning and their quantitative values.
Explanations of the four anomalies to the Aufbau Principle (Cr, Mo, Cu, and Ag) in terms of energy sublevel differences and Coulomb's Law.
This is a tough test for those who did not improve their explanation-writing ability. Since not a SINGLE student has come in to correct their previous explanations, I can only wonder how these explanations are going to be written and critiqued.

Today we continued our explanation of the periodic trend in atomic size across a period in order of increasing atomic number, and also the periodic trend in atomic size down a group.

Physics - we applied the concept of impulse as the source of change in momentum to several problems in the Momentum 1 worksheet.
We saw that the variables Fnet, t, m , vi and vf can be manipulated to solve for any one variable given the other four.

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 greater the number of protons, the greater the electrostatic force on an electron from these protons, and also 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 atom.
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 defined the term "isoelectronic" and gave examples of isoelectronic species.

Physics - we took an extreme case of acceleration, free fall, and calculated the apparent weight/normal force experience by a person - of course, the apparent weight was zero Newtons i.e. the person/being experiences weightlessness in a freely falling elevator.
We then discussed forces in EQUILIBRIUM, that is , their net force is zero; all of the forces balance each other overall. To find an equilibrant force, just find the resultant of the given set of forces, and draw/calculate an equal and opposite force to the resultant.

We discussed the properties of MOMENTUM (mass x velocity) and IMPULSE; these terms stem from a variation/derivation of Newton's 2nd Law.
We then did several problems applying these concepts and laws.
We began our Hooke's Law lab that shows the relationship between the force/weight applied to the spring and the distance that the spring stretches.

Physics - we discussed the meaning and source of "apparent weight", which is equal to the normal force pushing on the person/being.
We showed how the apparent weight varies when an object is in an accelerating elevator or space.

AP Chem - we began our redox titration assay of commercial bleach by making up the initial solutions, reviewing and calculating how to make a proper titrant solution of a desired concentration.

We reviewed the sources/causes of the exceptions to the Aufbau Principle.
We then wrote out the electron configurations of various cations.

Physics- took the multiple choice version of the quarterly exam; we then organized our lab folders.
You can have one missing lab per quarter; that one missing lab will not be averaged into your lab grade.

The labs from this quarter were as follows:
1st Quarter Labs

1. Relationship between Mass and Weight
2. Displacement Vectors College Tour
3. Graphical Analysis of Motion
4. Uniform Acceleration
5. Flight of a Tennis Ball
6. Throwing a Baseball
7. Net Force versus Acceleration

Make sure that all equations, units for each measurement, and unit cancellations. Make sure that there are units on all graphs, and that your line of best fit has about an equal number of lower and higher points.

On Friday, be ready to start our new unit on Force and MOMENTUM.

AP Chem - Enjoy your spectacular new textbooks; we will make good use of them as a supplement, especially since our edition of Brown, Lemay is tied to the AP/College Board objectives.


For HW, read CHAPTER 6 in its entirety (most of the information should look very familiar by now).
On FRIDAY, I will collect your homework answers to the following questions at the end of Chapter 6, and count it towards your second quarter average; show all work complete with formulas, units, and unit cancellations:
29, 50 , 52, 64, 70, 74

Physics - took the written-response part of the quarterly exam.

On the multiple choice part, look for questions regarding subtopics not covered as much on the written response such as:

Relative force of attraction problems involving two masses, m1 and m2 , at a distance, d, apart.
The class did not do well on that question on the Dynamics/Forces exam.
Go to the problems in the notes! Pick EASY numbers (1, 10, 100) in these questions and then use your answers to COMPARE the forces i.e. set up a ratio. If the original F is 100 N and the new F is 550 N, then the new force is 5.5 times the original F (just divide new force by the original force to get the ratio).
If you do not want to pick numbers, solve using the variables and simplify using F = (G m1 m2 / d^2); so anywhere you see (G m1 m2 / d^2) in your final answer, just replace that with F so that you can compare the forces.

Also expect "car chase" or "train crash" problems in which you solve for time or distance, using the motion formulas.

This test will also have questions from unit 1 on vectors.

Physics - we reviewed for the quarterly, a test that counts towards your quarter grade; the quarterly MAY also replace your LOWEST test grade, so the quarterly grade CAN count twice.

Tuesday's test is WRITTEN RESPONSE. There will be FOUR QUESTIONS, two on straight-line motion, one on projectile motion, and one on forces/dynamics.

Wednesday, we'll have the multiple choice part of the exam: 25 questions, about evenly divided among the four units.

We reviewed for the quarterly, going over the unit on vectors, straight-line motion, and projectile motion. Forces/dynamics is also on the test.
Keep checking Blackboard for today's notes and updated past test written-response answers.

AP Chem- we discussed the solutions to the Schroedinger equation, which takes into account the wave and particle nature of the electron as well as all proton to electron attractions and electron to electron repulsions in ANY atom or ion!



The solved equation yields FOUR quantum numbers that indicated the energy (and APPROXIMATE LOCATION, most of the time) of an electron in an element. we discussed the inability of the Bohr Atomic Model to account for many of the emission lines in all elements except Hydrogen. We then looked at the basis of the Quantum Mechanical Model of the atom, which treat the electron as a particle and a wave and accounts of electron-electron repulsions.



The Schroedinger equation solves for the "allowed" energies of all electrons in an atom.


Each electron's energy and approximate region is described by four quantum numbers: n, l, m(l), and m(s).


We then saw that the principal quantum number limited the angular momentum/azimuthal quantum number to a certain range of values. We also saw that the azimuthal quantum number determines the possible number of orientations that the orbitals can have in space. Magnetic spin number can be only one of two values: + 1/2 and -1/2.


We then applied this new information to earlier orbital language i.e. s, p, d, and f sublevels are associated with the azimuthal quantum numbers 0, 1, 2, and 3, respectively.
We noted that only the n and l quantum numbers determine the energy of the electron in an atom. With this relative energy information, we will assemble the relative energy sublevel order of the electrons in any atom via the "Aufbau PrincipLE/RuLE".

Zenyatta probably will retire now. Her final record was 20 starts, 19 wins and 1 second. The little-known back-story is that, after her 10th consecutive win, her owners became obsessed with her "perfect" record, and decided to run Zenyatta against the same or weaker competition time after time (except in last year's Breeders' Cup Classic, when most of her competition was severely compromised by a new artificial surface, on which Zenyatta had usually run). Zenyatta's lore blossomed, as the media kept drilling and repeating the word "perfection" along with the word "greatest". Overlooked was the more important term: "context". As Zenyatta racked up a string of victories against minor-league competition, through the practically unprecedented number 19, her legion of fans continued to grow, as did the hyperbole of "greatest of all time". Zenyatta's owners consistently skipped over races in which Zenyatta would have to face "the boys", a feat that is commonplace among better mares around the world.

Yesterday, though she finished second, her mettle was finally tested on a fair dirt surface against the best competition that she had ever faced. Though she is not the greatest horse who ever lived (see Secretariat, Man O' War, Citation, or Kelso, and you will LAUGH at the feeble accomplishments of ANY modern racehorse), she showed something far more important: that she could run, perhaps outrun, any horse of her era on a dirt surface (she has never run on grass- they should give her a chance to do so).

The same ethic applies to students. Many students can maintain a "perfect" 4.0 (or 4.3 or 5.0 or 8.0, whatever the ridiculous standard of perfection) by taking a suitably easy, unchallenging, grade-inflated course of (non)study. Such a path does not prove much of significance.

The more legitimate, worthwhile, and significant academic schedule is one that challenges a student to develop her/his abilities, though along the way the student may perform less than "perfectly"; the student might even encounter the greatest figurative teacher in existence: failure. There is nothing wrong with seeing what your limits are at a given point in your life, and then to take that feedback to readjust your schedule and pace.

Sometimes, you will be pleasantly surprised, other times you will be disappointed and forced to reassess your goals, but at least you should be proud that you did not waste your time excelling at very little.

Who knew that horseracing could teach people a lesson?

Physics - took part 2 of our Dynamics/Forces exam.

AP Chem - The 1st quarter multiple choice bonus exam (only available this quarter) will be given Tuesday after school. There is no makeup, due to the logistics and security of the exam. Your score cannot negatively affect your quarterly average but, if you score higher than your current average, your grade will be averaged in to your quarterly grade- there is no grade replacement.

Check Blackboard for a list of objectives covered on this exam.

Physics - took our Dynamics/Forces part 1 multiple choice exam.
We then finished the second Force vs. Acceleration lab in which we observed Newton's Second Law: Fnet = ma.

AP Chem - we did another electronic transition calculation, predicting first the expected type of EMR emitted.
We then discussed the failure of the Bohr Model to predict the emission spectra of ANY element, except that of a ONE ELECTRON system e.g. H, He +, Li 2+...

We also strongly reinforced the concept of Coulomb's Law and its relationship to potential energy:
the greater the attraction between positive and negative, the LOWER the potential energy, the MORE stable the system.

From this, we saw the He +, and Li 2+ not ONLY have lower PE principal energy levels, BUT ALSO that the energy DIFFERENCE between each corresponding pair of energy levels is DIFFERENT for each element, resulting in the emission of DIFFERENT and unique energy photons from each different element.

Physics- BE SURE TO STUDY THE REVIEW NOTES FROM TODAY (see Blackboard)!
We learned the universal law of gravitation with which we can measure the force of attraction of one object on another.
There are ONLY TWO factors that determine this ATTRACTIVE force:
1. the product of the MASSES of the two objects
2. the DISTANCE between their respective centers.

The greater the PRODUCT of the two masses, the greater the attractive gravitational force.
The greater the DISTANCE between the two masses, the LESSER the gravitational attractive force (by an INVERSE SQUARE proportion).

Tomorrow, we have the multiple choice part of the Dynamics/Forces unit exam.
There are NO QUESTIONS on Springs or Spring Constants (so ignore that part of the packet), and there is NO memorization of Dimensional Analysis conversion factors required (so ignore that page in the packet).
You should know, by now, that a Newton is a kilogram x a meter per squared second (that comes from Fnet = mass x acceleration).
Check Blackboard for all packet answers!
Tomorrow, bring in the HW questions that were due today so that I may give you credit for that work.

THE QUARTERLY exam will be given on Tuesday and Wednesday of NEXT WEEK. It will cover ALL FOUR UNIT PACKETS. The test will DEFINITELY COUNT towards your quarter grade AND, IF HIGHER, will ALSO replace your lowest test grade.
I will hand out the quarterly review packets/practice tests tomorrow.

No classes but check Blackboard for hw/notes/practice tests, etc.

Physics - continued our Forces 3 and 4 packet questions. THERE IS ONE CORRECTION! In Forces 4, question 1, we WERE solving for the coefficient of STATIC friction BECAUSE the object STARTED to accelerate from REST- ALWAYS associate any acceleration from REST with the coefficient of STATIC friction. That note was corrected and posted on Blackboard.
In each problem, ALL of the required information is given so that you can set up the diagram, and write the SAME equations each time. The only difference will be the unknown variable and/or whether the object is accelerating or not.
FOR HW to be checked on Wednesday; do QUESTION 2 on Forces 4. Also do QUESTIONS 1 THROUGH 4 on Forces 5 (ALL of those questions are review questions; check your notes, if you get stuck).
To help you study for Thursday and Friday's unit exam on Dynamics, I will post the answers (with detailed work shown) to MOST of the multiple choice questions at the end of our unit packet. Do those questions and then check your work vs. mine.

AP Chem- check Blackboard for HW tomorrow.
we discussed Planck's explanation of the blackbody radiation data curve in which he avoided the "ultraviolet catastrophe"/failure of the classical physics theories by hypothesizing that energy exists NOT ONLY as waves but also as discrete, indivisible packets of energy i.e. quanta of energy.
He explained the data by establishing the relationship between the energy of one quantum and the FREQUENCY of its energy when measured as a wave. His hypothesis was later supported/confirmed by Einstein.
We did some quantum calculations- determining the energy of a quantum/photon from either the frequency or the wavelength of a given type of light. We then magnified that to the energy per MOL of photons simply by multiplying by Avogadro's number of photons per mol.