Friday, February 1

We started todays class with the lab that we had started on Thursday. In this lab we were to carefully observe the line spectra of four unknown elements and to identify the four elements by comparing their line spectra to those of known elements. Mr. H told us about a website, http://astro.u-strasbg.fr/%7Ekoppen/discharge.html, where you can compare your spectra with the elements online.

After that we spent a few minutes going over the blog from Thrusday the Brooke did.

Next we started working on page 3 from the packet. Before we began, Mr. H warned us that this unit was going to be on of the most difficult units because it is the hardest to visualize.

The Quantum Mechanical Model of the Atom

Features of the Theory:

· Very mathematical

· Electrons are located in regions of space know as orbitals

· Each individual electron of an atom is described by 4 quantum numbers

· Each orbital holds at most 2 electrons

As we went through the rest of page 3 we added that information to our notebooks as well. The main idea was that each individual e- is described by four quantum numbers, which are n, l, ml, and ms. The first number is the principal quantum number. It is represented by the letter n, describes the energy level and size, and has the possible values of 1,2,3,… The second quantum number is represented by the letter l and determines the shape of the orbital. The quantum numbers n and l are related; l can take on any integral value starting with 0 and going up to a maximum of (n-1). This means that the possible values are 0, 1, 2, …, (n-1). Each principal energy level is has one or more sublevels. These sublevels are denoted by the second quantum number. In general, in the nth principal level, there are n different sublevels. Another method is to use the letter s, p, d, or f to indicate the sublevels l = 0, 1, 2, or 3. Each sublevel contains one or more orbitals, which differ from one another in the value assigned to the third quantum number, ml. This quantum number is used to describe the spatial orientation of the orbitals. For a given value of l, ml can have any integral value, including 0, between l and –l. The fourth quantum number, ms, describes the direction of electron spin. The ms value doesn’t describe the orbital; it describes the electrons in the orbitals. There are only to possible values for ms, +1/2 and -1/2.

After finishing those notes Mr. H instructed us to continue on to page 4.

The ways to remember orbital types:

Smartà spherical

Peopleà pinched cylinders

Don’tà dorky

Failà frog-shaped

(see chart below)

Lastly Mr. H said that we are learning about this stuff because it explains the line spectras and the elements in the periodic table, even the 14 that came after 1926, which Mr. H thinks is cool in a geeky way.

Light and Energy/Bohr Model of the atom TUESDAY, FEBRUARY 10, 2011

Mr Henderson started out the class by having us take out our packets and turn to page#13-14 to give us the correct answers to one of the webassigns due the previous day

(Pages 13-14)The answers to this webassign are:
1)a. Its predictions were inaccurate for atoms having more than one electron.
2)c. The best that one can know of an electron's location is to know the probability that it is in a given region of space.
3)d. Complex differential equations
4)b. Where an electron has a 90% probability of being located
5)b. The value of n cannot be negative AND c. The larger the n number, the higher the energy of the electron.
6)a. The value of l reveals information about the shape of the orbital housing the electron AND c. The value of l cannot be negative AND d. The value of l must be a whole number
7)b. The value of ml indicated the directional orientation of the orbital AND The value of ml must be a whole number
8)b. The value of ms indicated the spin direction
9)b. an l value of 1
10)a. TRUE b. TRUE c. TRUE d. TRUE e. TRUE
11)TRUE
12)b. 2
13)a. For every n value, there are just as many sublevels.
14)a. INVALID b. VALID c. INVALID d. INVALID
15)c. The 3s orbitals are larger than the 2s orbitals.

The class then looked at the blog from the previous day done by Dmitriy and Mr. Henderson had the class watch the video he added of the plane crashing into 12 feet of concrete.

Next the class took out their calculators and turned to page #1 to work on problem 4a. and 4b.
These problems will probably be the only time calculators will be needed to use for the rest of this unit.
The equation needed to remember for these equations is E=h*f=h*c/wavelength. f stands for frequency.

4a...red photon (f=4.80*10^14 Hz)

E=h*f=(6.62*10^-34)(4.80*10^14 Hz)=3.18*10^-19 Joules

4b...green photon (wavelength=5.43*10^-7)

E=h*c/wavelength=(6.62*10^-34)(2.998*10^8)/5.43*10^-7=3.66*10^-19 Joules

We continued the class period by turning to page #2 and started the problems in the chart at the bottom of the page.
Photon(Energy in Joules) use the equation from page #1
a. 3.03*10^-19
b. 4.09*10^-19
c. 4.55*10^-19
d. 4.85*10^-19
e. 5.00*10^-19
f. 1.64*10^-18
g. 1.93*10^-18
h. 1.06*10^-18
i. 1.55*10^-18

For these next problems use the equation En=Rh/n^2

• Rh is the constant called the Rydberg constant and its value is -2.180*10^-18 Joules.
• replace n with the number given in the problem.

E Initial(in Joules)
a.-2.42*10^-19
b. -1.36*10^-19

E Final(in Joules)
a. -5.45*10^-19
b. -5.45*10^-19

Change in E(in Joules)
a. -3.03*10^-19
b. -4.09*10^-19

The class was then given glasses that when put on revealed the true colors from white light included in roygbiv(red,orange,yellow,green,blue,indigo,violet)

We then also looked at different types of lighting which revealed different strengths of the colors from roygbiv.

At the end of the period the class ended the day by beginning a lab in the back of the room. The lab will be continued tomorrow

HW:next webassign not due till the 14th.

Waves that don't have anything to do with the ocean

Good morning students!

We began class today by talking about our test, and with Mr. Henderson saying how our scores were very spread out, unlike some other tests we may or may not have taken. Getting to the point we started the class with a discussion about atom models, and how said atom models were changed over history.

Firstly, let's start with John Dalton.

Dalton did not know how atoms looked, and didn't even bother trying to explain it to others. At least he wasn't a bragger. Dalton published his works during the early 1800s. Before him, only two men attempted to take a stab at the mystery of atoms: Socrates and Democritus.

Although this wasn't discussed in class, Socrates took a piece of cheese and cut it in half. Then he cut that in half. Then he cut that in half. So on and so forth, until he could not cut anymore. He called that the "atom".

Democritus had a slightly different approach.

He took some stuff, put it in a pestle, and crushed it up with a mortar. He called that "atoma" for indivisible. What these Greeks didn't know however, is that matter gets much smaller than even this! Stupid Hellenics. Sorry, Konstantine.

Back to the topic, we looked at Thomson next. He devised the "plum pudding" model. A sea of negatively charged particles inside an atom that looks like pudding. Yum.

Finally, Rutherford. He concluded that an atom is mostly empty space, simply because he fired alpha particles at a sheet of gold foil, and only a few bounced back.

We then proceeded to move on to waves, and how light consists of waves. Mr. Henderson brought up the class guinea pig to demonstrate. Will stood with one end of the coil to his cheek, and Mr. H interacted with the other end. The result was Will got hit in the face, and because of this, Mr. H showed us that you can get someone's attention simply by using energy. Wow.

Finally, what we did was we discussed different wavelengths. We went from the weakest to strongest, radio to gamma, and in between was the visible spectrum of color. We spoke about UV and how they settle in your skin, X-rays and how they settle in your bones, and gamma and how they go right through you. Oh and by the way, don't put your cat in the microwave. Its H2O molecules will start dancing.

Remember that video Mr. H talked about? That plane crashing into 12-feet of concrete video? Here it is.

http://www.youtube.com/watch?v=xM8E-CogkYE

There you have it. At that, we concluded our day.

Fact: Nukes contain gamma rays.

Friday, February 4

Class began with a review of Chris's blog from Tuesday. Then, Mr. Henderson announced that, as a result of the snow days, the test was pushed back to Monday. He also mentioned that lab notebooks will also be turned in on test day. Mr. H then provided us with suggestions on how to study. He reminded us of all the study materials we have available; such as the Moodle Review, Delicious bookmarks, unit packet, WebAssigns, and the textbook.
For a review, we did some problems in the packet. We started on page 22 with #9: For the enthalpy (delta H) of the reaction, the products are added and then the reactants are subtracted. When plugging in the standard entropy for just an element, it will always be zero. So for problem 9, the enthalpy should look like 2(o)+1(o)-2(-286)=572KJ. For the entropy (delta S), it should be 2(131)=1(205)-2(70)=372J/K. After finding this, the answer needs to be converted to KJ, so it should be .372. The next part of the problem is to find the temperature range using the equation G=H-T(S). The equation should be 0=572-T(.327) and the final answer should be 1749K and any temperature greater than that is spontaneous.
We then went to page 11 and did problem #1 to practice Hess's Law. The final answer for this problem was -221. To get this, the first equation was multiplied by 2 and the second was flipped.
Next, we did another Hess's Law problem. This one was slightly more difficult. The first equation was multiplied by 2, and the second and third equations were flipped. The final answer was -168.6KJ.
We then finished the Hess's Law Lab. The procedure was to first find Q, using the equation Q=mCT, then to find the moles, and lastly to find the enthalpy by dividing those results.

Tuesday February 2, 2011

Today began with the usual Web Assign reading sheet review, the answers to chapter 17:3-5 on page 35 were presented and explained in class. It is interesting to note that, according to Mr. H, J. Willard was A. a snazzy dresser, B. a real hunk, C. a true scientist, and D. a great uncle of Mr. H's. Unfortunately, the lack of any "select all" option posed a real challenge to students; this particular student happened to choose option C.

After that attempt at humor, Mr. H went over the previous blog post. Very helpful with explaining the conce

pts of entropy. The plan for today was to explain Gibbs Free Energy (ΔG), finish lab TC10 Reaction 2, and go over the Chapter 9 Quiz. Basically, ΔG is to be used to determine whether or not a reaction is spontaneous, non-spontaneous, or borderline (neither spontaneous nor non-spontaneous, the reaction can occur in either direction). The formula for finding Gibbs Free Energy is ΔG=ΔH-T*ΔS, where both ΔH and ΔS are in kJ and the temperature is in Kelvins. If ΔG was negative the reaction is spontaneous, if ΔG is positive the reaction is non-spontaneous, if ΔG was zero then the reaction is borderline. After that q

uick lesson, we turned to page 21 to practice using this formula.

Problem number 2 was a review of how ΔH and ΔS related to the spontaneity of the reaction. If both are positive the reaction is spontaneous at higher temperatures, if both are negative the reaction is spontaneous at lower temperatures. Moving on, it is important to always check that the units are the same before calculating ΔG. That is, T should be in Kelvins and ΔS should be converted into kJ.

On problem 6. c., although ΔG technically is a negative value, the reaction is classified as borderline. One's reasoning will vary from person to person, but in this case the ΔG value is so close to zero that the reaction would be classified as a borderline example regardless.

Next, we preformed Lab TC10 Reaction 2. Not all to different from the previous day's lab portion, for the most part the processes were identical. Since the data has been acquired, the conclusion/discussion will be done in class. After that little bit of fun, the Chapter 9 Quizzes were handed back to the students. Due to a grade calculation error, the multiple choice portion was graded out of 26 points instead of 22 points plus a 4 point written portion. Thankfully this error was fixed using some common sense and a rather fat Sharpie pen.

As for homework, the deadline for the Web Assign has been pushed back due to the snow day. Similarly, Delicious Bookmark assignments are due the next class day. That's all for now, enjoy a day without school!