Chemistry Entry 6

Thomsons "Plum Pudding" Model

Kicking off the week, our class dove into our new unit titled Unit 6 - Particles with Internal Structure. As with every new chapter, our class received and objectives sheet filled with goals that should be met by the time the test rolls around. We also got a worksheet concerning a famous scientist J. J. Thomas, and his experiments involving cathode rays. Cathode rays are beams of electricity emitted from the cathode of a high vacuum tube, while a cathode itself, in this case, is a negatively charged electrode by which electrons enter an electric device. A cathode can also be positively charged electrode, that supplies current for an electronic device. Thomson conducted several experiments in 1897 involving these rays, intent on trying to understand electricity. In class we were given iPads to go on the website A Look Inside the Atom, to answer questions on Thomson's three experiments, and the conclusions he drew from them. Out of the three, only two were accepted by other physicists, while the other one was proven to be incorrect. Out of the two hypothesis that were deemed correct, Thomson developed a model of an atom, titled the "plum pudding" model. It shows how an atom is made up of negative charged rays zooming around in a positively charged location, who sums up Thomson's observations during his two experiments.

Set-up for the sticky tape activity.

Building off of what we learned on Monday, on both Tuesday and Wednesday we concentrated our efforts on a lab with the driving question of: Do particles have charge interactions? We went about answering this question through fairly simple means, involving tape, tinfoil, and paper. Hanging from a stand stretched equidistant from each other, we placed the mentioned materials, with an added piece of tape. Once this was set-up at our table respective workspaces, we took two more strips of tape, stuck them together, and then peeled them off of each other quickly so as to fully charge both sides of the tape. This process was also done before taping the other two pieces of tape to the handle. To test if there were any charge interactions, we moved the tapes close to the materials, and found that both pieces of tape attracted the tin foil and paper, while the tape with the same charge repelled each other, and attracted when the opposite charges were placed near the other. We also discovered that as the tape moved closer and closer to whatever we were testing it with, their attractions would become stronger which was represented by them moving either closer or farther apart from one another, depending on the charge.

On Thursday we did an activity titled "Lets Conduct Maestros". Fifteen unique compounds were spaced throughout the room, and all we had to do was measure them to see if they were either conductive or not conductive. While most of them ended up not being conductive, about 1/4 of them didn't disappoint. Our table concluded that the substances which were conductive, were all similar in

One of the compounds we tested.

Explanation on why substances
have varying amounts of conductivity.

 that they were all positively charged metal ions, found in an aqueous solution. From this activity, I also learned of a classification called "salts", which are merely positive ions from a metal combined with negative ions from a nonmetal. An example of this is sodium chloride (NaCl).

Electrolysis of CuCl(II) diagram.

Finishing up the week, on Friday (MOLE DAY) each table group recorded their own observations of a lab set-up concerning the electrolysis of copper chloride, or CuCl(II), which had been set up the previous day. Set up in a U-shaped test tube, on the right side a negative electrode gave off a current, with a positive electrode feeding a current on the other side. What I immediately noticed was that on the positive side bubbles were forming that gave off the scent of chlorine, while on the opposite side a weird pink substance was forming on the electrode surface. As I eventually learned, the "pink stuff" was actually copper forming, due to the positively charged copper sulfate and hydrogen ions attracted to its opposite charge. While this was occurring, the negatively charged chlorine ions were attracted to the positive electrode, resulting in the chlorine smelling bubbles forming on the surface. I found that collaborating as a class with our separate data results, concerning each activity we completed throughout the week, helped me to understand the material a lot more, compared to if we had continued moving on instead of sharing our results. I would like to work a little more on understanding the relationship between positive and negatively charged ions, and how the combination of different elements effects their conductivity.

Chemistry Entry 5

Simple mass & mole problems.

Two problems I initially had difficulty with.

Our class began the week with reviewing our homework we had been assigned over the weekend. These problems consisted of calculations involving moles, various elements,  and the masses of assorted objects. Each problem varied in that you were given a specific amount of information, but each time the given information was divergent, so the unknowns had to be solved differently than usual. Sometimes more than enough information was given, so the reader had to be able to understand exactly what was being asked, and had to know exactly was was needed and what wasn't to solve the problem. Personally, I had a lot of difficulty in solving problems such as these, mainly because whenever I see something given that is unneeded, I fail to grasp the fact that the information is irrelevant to the question. This is partly due to me still learning about the material and that I am collecting more knowledge about how to solve these types of problems, but I also need to get over the mental roadblock I have in terms of problems like these. What really helped me begin to figure out how to tell which information was needed or not, was white boarding the homework as a class. I heard all of the input from my fellow peers and the various ways they went about solving the homework, and was happy to overhear that I wasn't the only student struggling with this. Solving out difficult problems such as these always seems to cause a light bulb to go off in my brain, and everything seems to click all it once. I would love to continue white boarding out problems as a class, as this learning style really seems to stimulate my learning abilities.

Solving for the empirical formula.

Finding the empirical AND molecular formula's.

Our next task was a worksheet involving Empirical and Molecular Formulas. I learned that the main difference between these two is that empirical means "based on experimental data", and the molecular formula is simply a formula giving the number of atoms of each of the elements present in one molecule of a specific compound. To solve one of these types of problems, you have to be given the grams of the specific elements, and have a periodic table present so as to find the atomic number of the given elements. Once located, for each element, you multiply the given mass of the element by 1 mole, which is then divided by the elements atomic number. Once you have solved that, you compare the numbers between the elements, and whichever is smallest, you divide all them by that amount. The approximated answer of this is simply the amount of the elements present in the empirical formula equation. If you're then instructed to find the molecular formula, all you have to do is add up the atomic numbers of the given elements, and then divide that number by the molar mass of the compound.

I'm a dingbat!!

The rest of the week consisted of a quick quiz and then studying for our test on Friday. The quiz seemed easy to me when I took it, but as it turns out, I made a really stupid which earned me the title of a "Ding Bat." I accidentally had multiplied an O, mistaking it for a 0 while it actually stood for oxygen. I somehow over looked this incident and had an interesting surprise when we were handed back the quizzes. In terms of the test, I felt a lot more comfortable and confident than I felt on the quiz, with nothing surprising me or striking me as being too difficult.

Chemistry Entry 4

Mole fact.

Continuing into what we started the previous week, this week our class delved further into Unit 5. The first thing we covered was the topic of Relative Mass and the Mole, and how we could use them to count atoms by using just a balance. I was familiar with relative mass, but a mole was an entirely new concept for me, that I am still trying to understand as we progress further into using this measurement. A mole is the mass of a substance (in the case of the worksheet; oxygen and sulfur) containing the same number of fundamental units as there are atoms, in the specific number of 6.022 x 10e23. The units of a mole can range anywhere from a molecule to an atom, but they always have the same number. This number is called Avogadro's number, with Avogadro being a famous scientist we discussed about in Unit 4. Back to the worksheet, we were given a table of oxygen and sulfur atoms, and needed to find the mass of the sample, through knowing the number of atoms in that sample. This could be found through multiplying the mass of the first sample (contains one atom), by the number of atoms in each column. Once this was completed, we made a ratio between the oxygen and sulfur atoms, comparing the number and masses of the atoms. Our table came to the conclusion that, the ratio of the sample masses will be equal to the ratio of the atom's masses. We also realized that, by knowing the relative masses of the above elements, you can use them to "count" atoms, with the quantity being the mole. As the unit Mole can be confusing and  add complexity to an "average" question, the next day we burrowed deeper into this enormous number. To give somebody an idea of how massive a mole is, if we had a mole of rice grains, all the land area of the earth would be covered with rice to a depth of about 75 meters.

Heating up the substances.

Post heating.

In addition to the problems we solved regarding the unit mole, last week we did a lab called the "Empirical Formula Lab", empirical meaning based on previous experimental evidence.  In this experiment, a specific amount of zinc was mixed with hydrochloric acid. With our table groups, we had to collect data that would enable us to determine the empirical formula of zinc chloride (Zn?Cl?).  This lab took two days to complete, as the reactants needed a specified amount of time to combine. On day 1, all we had to do was find the mass of a regular, empty beaker, and then add zinc pieces to find the mass of both the zinc and bottle. Once this was complete, we had to add 3 moles of hydrochloric acid, so we could place the beaker in a safe location so as to finish the rest of the lab the next day. Picking up where we had left off, day 2 was slightly more complex, for me at least. recording the observations in day 1 just involved us to examine and interpret what was occurring, but day 2 required a little more calculation. Our workplace was set up to enable us to heat the beaker, so as to remove the unneeded water from the zinc chloride. Our only restriction was to remove the heated beaker immediately off the bunsen burner, if the contents began smoking. Once the zinc chloride was finished heating, it was interesting to see how it solidifies from its molten state. Once this process was complete, the mass of the beaker and zinc chloride had to be found twice. The idea of measuring it twice was to verify that the second mass is lighter than the first (by approximately .02 grams).

White boarding of question 8.

Finishing up the week, as a class we white boarded a worksheet involving problems with sealed sample containers. We had to find the mass of said containers as well as of its contents. A new vocabulary word I learned from this was Tare Weight. Tare weight is the containers empty mass, and is helpful as the number is needed for various calculations throughout the sheet. The questions varied, but the main idea of this was to learn how to find the number of moles or atoms in a container, given a formula. The formula of the contents is incredibly useful as you need to multiply the number of atoms in the formula, by their respected average atomic numbers, so you can plug it into the main equation once all the values are found. I found this week slightly confusing due to the mole, but also intriguing as you can apply the mole multiple chemistry concepts, which helps me to understand them more.

Naturally, I enjoyed the below demonstration you gave for our class.

I took a video and then screen shotted this!

Chemistry Entry 3

Starting off our week in Chemistry, Monday was our designated review day for the Unit 4 test, our first one this trimester. Previously on last Friday, our class acquired an objective sheet illustrating main concepts that we needed to know for the test on Tuesday. The listed concepts on the sheet were everything we had covered in the weeks leading up to the test day. Within our table groups, we filled out the boxes on the sheet to the best of our abilities without using our notes, referred back to them once everything we remembered was written down, and then white boarded the worksheet to share our answers with the class, as shown below.   

I really enjoy this type of learning as it is an easy way to place yourself in terms of understanding the material and noticing where you are in comparison to your peers. Also, through white boarding review packets like this, if you noticed you made the same mistake as someone else, than you can work together to solve it or bring it up as a class discussion. Similarly, you can scan another groups board to see if they solved any problems differently and possibly in a simpler fashion, or query on how they got a specific answer that your group might not be sure on. Either way, I recognize that this type of review session is beneficial for a quality test score, although I am still curious on what points I lost as they are yet to be handed back.

The Monday review session for our Unit 4 test was composed of filling out a review packet, similar to what was completed on Friday. This one differed from Fridays because it contained actual questions that could appear on the test but in a different format/new scenario. Using the same whiteboard form of study, we concluded our worksheet and updated our whiteboard. A concept I found interesting was that atoms can be monatomic, diatomic, triatomic, and so on. I was aware that atoms differ depending on the element, but unaware of the specific classifications and how to demonstrate the differences in a particle diagram. I had a bit of difficulty diagramming how atoms of different classifications (say monatomic and diatomic) compounded together to create a new element, but by white boarding the problem out, I had it down in no time. The only other problem I faced was was not mixing up the definitions and properties of mixtures, compounds, elements, atoms, and molecules. I continuously quizzed myself on this topic both in class and out, but I'm worried I haven't mastered it as I believe those were the scarce problems I incorrectly completed on my test.



Kicking off our new unit, like last time, our class received a list of objectives that will be taught through the course of the next unit, which is Unit 5 - Counting Particles. Our first activity had to do with a worksheet focused on Relative Mass. The purpose behind this was to determine the relative mass of different kinds of hardware and to learn to count by massing. We were given a semi-filled out data table, that contained multiple different types of hardware (bolts, washers, hex-nuts) and an empty container. We had to find the general mass, mass of 25 pieces, and the mass of 1 box. This was calculated through a scale, and guided with knowing that 1 kilogram is equal to 1,000 grams. Throughout the rest of the sheet we had to use the given information to solve problems, given various scenarios and new bits of information to add to the calculations. I definitely still need to work on problems like these as I am always either at a loss on how to approach the problem, or am on the right track but still don't understand parts of it.

As Friday was pep rally day, I had to leave early for the marching band. However, I am aware that the worksheet that was covered in the short amount of time had to do with Molar Masses of the Elements. I would like to cover this on Monday as a refresher to the kids who learned it, and as new material for us marching band nerds.