Thursday, September 30

Meet the Elements, by They Might be Giants, was the first thing to greet us after entering Mr. Henderson's classroom. After the song ended, Mr. H said that today's lesson would be about forming the families of the Periodic Table. He then went over tonight's homework: a WebAssign on the PT due Friday and write ups on Labs 3 & 4 due near the end of next week.

After that, Mr. H quickly reviewed the periods and groups of the PT, organized by atomic number and chemical properties respectively. Then, we filled page 4 of our packet which covered the physical & chemical properties of certain elements.

Number 8 was reminiscent of the Mendeleev for a Day Lab as we had to organize the elements by atomic number and chemical property. Family # 1 included Aluminum and Gallium because 2 molecules of either and 3 molecules of Oxygen form a compound: Aluminum/Gallium Oxide. In addition, only one molecule of either and 3 molecules of Chlorine form the compound Aluminum/Gallium Chloride.

On the other hand, Family # 2 includes Beryllium, Magnesium, and Calcium. Only one molecule of any of the 3 and one molecule of Oxygen form Beryllium/Magnesium/Calcium Oxide. Plus, only one molecule of the 3 and 2 molecules of Chlorine are needed to form Beryllium/Magnesium/Calcium Chloride.

After organizing the elements into columns, they only needed to be rearranged into rows based on atomic number. The easier task, I'm sure.

The next thing Mr. H showed the class was last night's blog entry, it was quite impressive. Then he went over how to write up Lab AMI 4, the key point being that it be organized.

We skipped over to packet page 17, covering the specific groups in the Periodic Table. His word of advice? "Get to know your PT."

Probably the highlight of the day for most of the students was the "Potassium video." An educational video clip demonstrating how this particular element reacts violently with water. A lot of people found it funny and, well, just see for yourself.

Well, no one can say science is boring. Mr. H promised us the next day he would be dumping a chunk of Sodium, should be interesting to see it in person. Approaching the end of class, we concluded with page 3 of our packet.

(Pretend page 3 is here.)

For the groupings: AM=Alkali metals, AEM=Alkali Earth metals, and ML= Metaloids. Well, that's all for now. See ya tomorrow!

Wednesday, September 29

Today, Mr. H started off the class by telling us to wipe down the lab tables with a wet paper towel after a chemical lab. He said that we should do that every time we work with chemicals in order to have safety precautions. After that, we admired Natasha's blog that she did the night before. He reminded us that there is the site called DropShots and it is where all of the pictures go from a lab or a demo that day. If you are the scribe, then you can use it to get some pictures.

He then told us to get our lab notebooks out. We were to do Mendeleev for a Day Lab (AMI4) and the Oleic Acid Lab (AMI3). He summarized what we were supposed to do while we wrote down the purposes of the labs.

He told us to find a partner, or if we preferred, work alone to do this lab. Mendeleev for a Day is a lab that required the sheet that was given to us yesterday. It had 20 squares and we were supposed to cut them out for class. Each square had the Atomic Mass, the melting point (degrees C), the boiling point (degrees C), the number of O in oxide, and the number of Cl in chloride. Those were two chemical properties of the element and also two physical properties. We were to start putting the squares in order from least to greatest according to the atomic mass in a row. From there, you were to look for common points, and to move them into columns. More specifically, the number of O in oxide and the number of Cl in chloride. These columns are called families. Mr. H gave an example of his own family. Mr. H's father had a specific way of walking. If you look at him and then Mr. H, you wouldn't see a difference. He also gave us an example of the males in his family get gray hairs around their 30's. He told us this because it relates to the lab. Families have similarities and in the periodic table, the columns have similar properties, putting them in the same "family." Anyways, after we put them in columns, we taped them into the Data section in our lab notebooks. Remember to put the squares on the paper landscaped. This provides more room for the squares. Or, you could put it across two pages in your lab notebook like this (left):


The Oleic Acid Lab is much different. We were working with lycopodium powder. Lycopodium powder is made out of a type of moss, and can trigger some allergic reactions, if you are allergic. Oleic acid does not mix with water, but dissolves the lycopodium powder. The first thing we did was put our safety goggles on. At our lab stations, there was already a yellow tray with water. We were to gently put the lycopodium powder on the surface of the water until it looked a little filmy. Mr. H did a little demonstration on how to do it:
This is how it looked like (bottom):

Then, when we were ready, Mr. H came around each lab group to put a drop of oleic acid into the tray. What we observed was that the oleic acid dissolved in the lycopodium powder, but in the process, it spread out on top of the water. It had a large diameter. This is what the oleic
acid looked like after Mr. H put it in the tray. As you can see from the picture, it dissolved the lycopodium powder and made the water easier to see through. There is no more of that filmy look.

Mr. H gave us a sheet of paper to record our data in, and the number of drops/mL of .500% oleic acid solution is 32. We decided that the average diameter of the drop was 14.8 cm. You are to find the surface area, height, length, width, volume, and mass. For homework, we are to finish the data sheet and the conclusion/discussion for both labs. See you tomorrow!

Tuesday September 28, 2010.

Today Mr. Henderson started out the class by reviewing last nights scribe's blog. He went over all the plus points of it and went into further detail on how the blog reviewed what we did in class the previous day. He also talked about the 5 postulates. He then told us a little about what we were going to do today in class. Today in class our main goal was to learn about the atomic structure, atomic number, and the mass number.He then started to review page one in the packet. We went over most of it yesterday but we finished up today. We talked about how the Dalton theory of an atom was just a circle with the element name inside. There was no proposed structure to it. The JJ Thomson theory of an atom was that it looked like plum pudding. The Rutherford theory was that positive charges were concentrated in the nucleus which was in the center of the atom and then the electrons surrounded the empty space outside the nucleus. Bohr's theory of the atomic structure was that electrons are in orbit around the nucleus. Bohr's structure also only worked for hydrogen.The picture on the left shows these structures.

Before we continued our lesson on the atomic structure, Mr. H gave us a demonstration on how the cathode rays work. He gave us a little background information on who and how it started. In 1896 British physicist J.J Thomson showed the rays were composed of a previously unknown charged particle, which was later named the electron. The first picture shows the cathode ray empty. After putting some electricity conductivity you see a neon greenish light go through the tube. The second picture shows what happened when the electricity is conducted through the cathode tube and a magnet is put on top. The ray is reflexed to the top when the positive side of the magnet is put up. The third picture shows the same thing as in picture two just a variation. Picture number four is what the cathode ray looks like when the negative side of the magnet is put above it. Picture five is just what the cathode ray looks like when electricity is conducted through it.

1. 2. 3. 4. 5. 6.

After the completion of page one, and the demonstration, Mr.H gave us a little lesson on the atomic structure and there were notes on the board so we could follow along. The notes basically summarized everything that we needed to know to do page number two. The atomic number is the number

of protons plus the number of electrons. It is the identifying property of what the element is. The mass number is the number of protons plus the number neutrons. The mass number is on top and the atomic number is on the bottom as showed in the picture. On the other side of the atomic symbol there would be either a +, -, or no sign there. This determines the charge of the electron and the over all change. It also determines whether it is a positive, negative, or neutral charge. The symbol and the subscript go together. We then continued to talk about isotopes. Isotopes are different types of atoms of the same chemical element, each having a different number of neutrons. They also differ in mass but never in atomic number. The number of protons is the same because that is what characterizes a chemical element. We took the element carbon as an example. On the periodic table when you see the element carbon, you see its atomic symbol, the number of electrons its has, and you see a number at the bottom called the super script. The super script is the average of the mass number of the atomic element. For carbon on the periodic table it shows 12.01. This means that the most abundant isotope of carbon has a mass of 12.01. Mr. H then explained the different between an Ion and an Atom. An Ion is a charged particle while an atom is a neutral particle.

We then turned to page to and completed the chart. The chart helped practicing important skills such as knowing how to find the atomic number and the atomic mass and the number of protons and neutrons and the number of electrons of any given element. Here are the answers to the chart.

The last ten minutes of class we reviewed our unit one tests. Mr. H went over the frequently missed problems. He went into much detail on why these problems were wrong. Toward the end of class he passed out a sheet of paper called the "Mendeleev For a Day." There are 20 squares on this paper that you need to cut out for tomorrows class to play the game! Cant wait!

Monday 27, September

To start off class, Mr. Henderson clarified any information that we may have missed concerning the TLC and the tutors there. He told us that if we were struggling in Chemistry, we could visit the TLC for help from actual science teachers or AP students as well as visit Mr. H early in the morning. We then moved on to the subject of the day; The history of the atomic model and the various scientists that helped create each one in their respective times.

On Pg. 15 in your chemistry Unit2 packet, there is a very general history concerning the atomic model starting with Dalton. However, Mr. Henderson told us that the first ever recorded theory concerning the atom dates all the way back to Ancient Greece and a philosopher by the name of Democritus. Democritus argued that he could chop a piece of papyrus into halves and halves and halves until he would reach some sort of building block that could not be broken down any further into a smaller or simpler form. He called these building blocks atomos and he believed they made up all matter. Democritus had no idea how accurate he actually was, but for nothing more than an educated guess, this was a remarkable theory. It is important to note that Democritus never actually tested this theory using science and therefore, he is regarded as a philosopher rather than a scientist. It was not until the late 1700's and early 1800's that the scientific revolution ushered in a new wave of interest in the field of atomic structure.

The next man to take a stab at an accurate atomic model was John Dalton. This scientist used the scientific method of developing a hypothesis and testing it to form a theory. He called these theories postulates, or basic rules. The five postulates that Dalton formed are as follows.
#1) All matter consists of atoms

#2) Atoms are indivisible (cannot be broken down any further)

#3) In a chemical change or reaction, atoms simply rearrange themselves but never turn into any other atoms. This is demonstrated in the picture below in which Hydrogen and Oxygen combine to form H20.



#3 (continued) Also, atoms never gain or lose mass in any way during any chemical or physical change.

#4) Compounds have a determinable amount of atoms and always have the same amount of each atom.

#5) Law of Constant Composition. All Compounds contain the same amount of each atom no matter where the compound is found or under what circumstances.

These 5 postulates are still seen today as a basic level in understanding the structure of atoms and compounds. Dalton never did create a finite model that he believed was what an atom might look like. He did however represent an atom as a circle with a symbol on it, such as H for Hydrogen.

Proceeding John Dalton, J.J. Thomson was at the forefront of the atomic model issue. J. J. Thomson believed that atoms did not only consist of alpha particles, but also possessed some other feature. By separating the alpha particles from a beam of light and firing this beam, known as a cathode ray, through a glass tube with positive or negative plates on either side Thomson was able to test this. After seeing the cathode ray bend towards the positive plate, Thomson was able to determine that the are other particles that make up an atom and that they are negatively charged. Thomson called these negatively charged particles electrons. This lead Thomson to relate his atomic model to the favorite desert of England at the time, earning it the name The Plum Pudding Atom. Thomson believed that atoms consisted of moving negatively charged electrons that are immersed in a sea of positively charged stationary particles. The model looked something like this picture, with the dots being electrons and the red material being the positively charged "sea".





For many years, A scientist by the name of Ernest Rutherford studied this model and debated it's accuracy. To test the Thomson models validity, Rutherford set up an experiment in which he took a thin (only a few hundred atoms thick) piece of gold foil and placed it in a container which had sensors on either side while shooting a stream of atoms in its direction. If Thomson's model was correct, the atoms should have gone through the gold foil with no problem and triggered only the sensors on the other side. What Rutherford found was that although most of the atoms did behave this way, 1 out of every 10/20,000 deflected off of the foil and reflected back at an acute angle. Rutherford was quoted saying "Its as if you shot 20,000 bullets at a tissue with most of them going through the tissue with no problem, but 1 out of every 20,00 of those bullets would reflect back at you!" Rutherford was amazed at this and determined that atoms were not full of positive particles, but were rather made up mostly of empty space with 99% of its mass concentrated in its nucleus, earning his model the name The Empty Space model. Rutherford still did not know how the electrons were distributed across the atom, leaving his model still somewhat inaccurate

Finally, one of Rutherford's colleagues, Niels Bohr, measured light energy to more accurately determine where the electrons would be relative to the nucleus of the atom. By measuring each layer of electrons of an atom and observing the light they emitted, Bohr was able to establish the general amount of electrons and their area relative to the nucleus. The downfall to Bohr's method was that once he began getting into the atoms with more electrons, such as Gold, his estimates were off by more than 20-40% at times. However, Niels Bohr was able to develop an atomic model, known as The Planetary Model.

Neils Bohr called it this because he thought that the electrons orbited the nucleus much like moons orbit a planet. This is the most accurate of all the depictions discussed so far.

To wrap up the class, Mr. Henderson gave us the answers to page 15 which are as follows:

1: b
2: d
3: c
4: a
5: c, b, a

We also drew sketches of what each scientist, (Dalton, Thomson, Rutherford, Bohr) believed
that atom looked like and those can be seen by asking me or any other student before or after class. Tomorrow, we will incorporate verbal explanations with these visuals models to describe each scientist views on concerning the structure of an atom.

Friday, September 26

Today’s class was very . Mr. Henderson was not in class today, so we had a substitute. Our class began when Mr. Doody from the TLC came to talk to our class. He told us about how great the TLC is for helping with chemistry, as well as all other classes offered at GBS. Mr. Doody also advised us to frequently use the textbook as a study tool and not to spend more than ten minutes on a problem. We then went to the computer lab to do the Rutherford Simulation Lab, which is a computer activity. We were given a sheet that gave us all of the directions for the lab. We went to the website http://phet.colorado.edu/simulations for the lab, which was completed in our lab notebooks. After completing this lab, we went to http://www.blogger.com/chemthink.com to do the atomic structure tutorial. After completing the tutorial, we filled out a table on the lab sheet.

The answers should look like this:

Once we completed the lab, we were supposed to cut the table and put it into the left side of our lab notebooks. For homework, we had to finish the lab if we had not already in class.

Today’s class was very productive!

Thursday, September 23 - Unit 2

Today marked the official end of Unit 1 as we took the Unit 1 Test. There were 35 multiple choice questions and a page of long answers.

The unit involved a lot of learning - much of which was unrelated to course content yet nontheless important. Consider all you have learned that is not normally associated with chemistry:

• How to do a lab report
• How to remain safe in a laboratory
• How to find our course page at gbschemphys.com
• How to use ChemThink
• How to use WebAssign to do a reading sheet
• How to use WebAssign to complete a question/problem set
• How to use the Graphical Analysis software package
• How to use Delicious to make and share a bookmark
• How to use log in and create a blog post

Now that we have learned the Chemistry Basics and mastered the logistical items above, we will move a little quicker. The second unit pertains to Atoms, Molecules and Ions. We begin Friday with a laboratory.

Wednesday, September 22

Today’s chemistry class was very interesting. The period was shortened due to late arrival, but we managed to learn so much! We started out the day a little differently than usual by getting our lab notebooks back. Although we turned them in on Tuesday, Mr. H worked through them quickly to get them back to us before our test. On the subject of the test, Mr. H would like to remind everyone that the Unit 1 test will be on Thursday, September 23. He explained to us how the test would be 35 multiple choice and 3 short answer questions. One student asked questions about knowing labs for the test, and Mr. H reassured us that knowing specific details from labs was not necessary. Mr. H also gave us some very great advice regarding studying for the test. He said that if we signed onto our moodle account and went to the Chemistry Honors 173 Metacourse that we would find some great test preparation worksheets. I did this and found that they were incredibly helpful. One other resource that Mr. H hopes we will use to study are the links on the Delicious page. If you go to the class website, you will find some links to those articles.

The next activity we did in class was to talk about the previous nights Webassign. Many students, myself included, noticed how some of the questions on the Webassign were particularly difficult, namely the last problem. It was requested that we go over that problem, so Mr. H generously took about 5 minutes to explain it. Here is the work that was done:

After explaining the problem, Mr. H went on to say that spending more than 30 minutes a night on a Webassign was unneeded. He explained how missing one question on one Webassign for one night for one unit for one semester was completely okay. He also added how sometimes he will make a Webassign less points than he originally planned, like making a 10 point Webassign into a 7 point Webassign.

After the Webassign talk, we went over Kyle’s blog from the previous day. Mr. H was very impressed by how thorough his blog was.

After this, Mr. H asked us to take out our new unit packets, and thus we started unit 2. This packet is titled Atoms, Molecules, and Ions. It has a picture of the periodic table on the front page. We then proceeded to begin lab AMI1: Probing the Black Box. Each group of two was given a small circular box with a silver ball inside. Our job was to figure out the structure inside of that mystery box. Some possible structures were:

or

or

For this lab, we were told to only fill out the purpose and the data section with a picture of what we thought the inside of the mystery box looked like. Mr. H said that we would do a conclusion section as a class on either Friday or Monday. The class ended here, and as we gathered our belongings, Mr. H reminded very animatedly to study for our test the next day. Today’s class was very productive and fun!

Tuesday, September 21

Mr. H started off class by telling us to turn our lab notebooks in with our lab rubric in them. He also reminded us that our test is on Thursday and our 1.3 Density WebAssign is due tomorrow. We then looked at Brooke's blog which was filled with useful information about the test. After this, Mr. H told us toady we would review for the test and then finish our Beverage Lab. He then showed us that he added our Delicious bookmarks to the blog as resources to study for the upcoming test. However, some peoples' bookmarks aren't on the page, so Mr. H told us to check to see if we have the right tags: hcp3y1011 and unit 1, or the Delicious website isn't functioning properly.

Mr. H then told us to get out our review packet and turn to page 19 which was the density reading sheet. Since we had already gone over problems 1-6, we only went over problems 7-14. The answers for these problems are:

7. C; temperature

8. A; increases

9. B; 63 degrees

10. B; 35 grams

11. B; they absorb certain colors of light and reflect the rest to our eyes.

12. D; bluish-green

13. D; 820nm

14. C; reddish-orange

Mr. H told us while we were writing down the answers that these types of questions would be on our ACT. Some questions would be easier like question 7, while questions like 14 would be more challenging.

After we wrote our answers down, Mr. H reviewed temperature and accuracy vs. precision. The three major temperature scales are: Fahrenheit, Celsius and Kelvin. The formulas for finding temperatures are: *F=1.8*C+32, *C=(*F-32)/1.8 and K=273.15+*C. The boiling point of these temperatures are: 212*F, 100*C and 373.15K. The freezing point are: 32*F, 0*C and 273.15K. For additional reference, use page 8 of the book. Mr. H showed us a picture of three dartboards with one portraying inaccurate and imprecise throws, the other portraying accurate, but imprecise throws, and the last one portraying both accurate and precise throws. Here is a picture relating to this idea.

After this, Mr. H reviewed the classifications of matter on page 16. The answers are as follows:

A. HOM

B. HEM

C. E/C

D. HEM

E. HOM

A. C

B. E

C. C

D. HOM

E. HOM

F. HOM

G. HEM

H. HEM

I. HEM

J. HOM

A. F

B. F

C. F

D. T

E. F

F. T

G. F

Some key classification of matter terms are element, compound, homogeneous mixtures and heterogeneous mixtures.

Element- Type of matter that cannot be broken down into two or more pure substances. Ex. Oxygen

Compound- A pure substance that contains more than one element. Ex. Water is a compound of oxygen and hydrogen.

Homogeneous mixture- The composition is the same throughout, also known as a solution. Ex. brass is a homogeneous mixture of zinc and copper.

Heterogeneous mixture- The composition varies throughout. Ex. Granite contains discrete regions of different mixtures (feldspar, mica, and quartz).

After we finished reviewing, Mr. H told us to finish our Beverage Lab. Two group members of each group went to the computer lab to graph the data while the other group members found and recorded the data of two beverages. My group chose apple juice and berry juice. The volume was 5mL for both juices and the mass ranged between 0.75g and 1.15g. The density of apple juice and berry juice was between 0.15 and 0.23 g/mL.

Once we finished, Mr. H told us to write a Conclusion/Discussion for the lab and make sure we had the graph attached to the data sheet. He also said if your group didn't finish, finish it and hand it in at the start of class tomorrow.

Monday, September 20

Today Mr. Henderson started the day out by signing up the remainder of people for blog days if they have not already done the blogging. He then goes on to tell our class that today we will be doing a lab test. The lab test will be done throughout today and tomorrow.

Homework: Labs #5, 6, and 7 are due Tuesday (tomorrow)

webassign is due Wednesday

TEST THURSDAY

FOR THE TEST, STUDY FROM THE BLOG, TEXTBOOK, AND OBJECTIVE SHEET FOUND IN THE UNIT PACKET.

A sheet was then handed out explaining what should be included in the labs which will be turned in tomorrow.

Mr. Henderson then began to explain what our class is going to be doing for the rest of the week. Tomorrow we will continue working on the sugar lab and then have a lab test. Then we will review for the test Thursday. Wednesday we will be starting to learn about the next unit. Thursday is the test and on Friday first someone from the TLC will be coming to talk to our class and then we will be going to the computer lab.

Next Mr. Henderson told our class to take out our Chemistry Basics packet while he opened Anthony's blog from the previous day (Friday). After looking at the blog we turned to page 13 in our packets and worked on problem #5, which said if a piece of aluminum has a mass of 14.0 g, what volume does it occupy?(the density of aluminum=2.70 g/cm cubed). To find the answer, Mr. Henderson set up the equation volume=mass/density=14.0g/2.70g per cm cubed. The answer when put into the calculator came out to be 5.185185185185. Using the significant digits rule the answer is 5.19 cm cubed. We also learned the answer could be 5.19 mL because cm cubed equals mL.

The next problem we did was #11 on page #14. The question was several beads of an unknown metal are placed into a partially-filled graduated cylinder. The water level in the graduated rises from 24.58 mL to 49.12 mL. The mass of the beads was determined to be 127.88 g. Determine the density of the metal. To solve the problem Mr. Henderson set up the equation density=mass/volume=127.88g/24.54mL. The volume was found by subtracting 49.12-24.58=24.54 mL. 127.88g/24.54mL=5.21108. Using the significant figures rule the answer is 5.211g per mL.

Once we finished the 2 problems Mr. Henderson went on to tell us that for our test on Thursday that we will have to know how to do the percent difference(difference between the 2 measures/average of the 2 measure x 100) and find the density of a substance(density=mass/volume).

Then it was time to start the lab for the day. Mr.Henderson explained that the purpose of the lab is to determine the percent sugar in each of the beverages. What percent of the beverage is sugar? The reason why we would want to know this is because sugar contributes to the mass. The beverages used are made mostly of water and sugar but also flavorings and dies.

Today we did the first part of the lab which was finding the mass and volume of water that had either 0%, 5%, 10%, 15% or 20% of sugar in it. These measurements would be used to determine the amount of sugar in the beverages which would be tested tomorrow. Mr. Henderson then reminded our class to wear our safety goggles and to dispose of the sugar water in the sink. Also he then explained how to use the pipets by turning the wheel.

In the lab, as expected, it was found that the more sugar the water contained, the higher its mass. The mass of the 0% sugar water was 4.97g, 5% was 5.03g, 10% was 5.07g, 15% was 5.16g, and the 20% was 5.25g. The volume of the 5 substances was a constant 5.00 mL.

This is a picture of my lab group’s data table from lab #8

This is a picture of the rubric which will used to grade the labs.

Friday, September 17

On Friday the first thing that Mr. Henderson asked the class to do was pull out their Unit 1 Packets and a calculator. He then told the class that we would not be staying here long, we would be going to the computer lab to do some graphing and plotting on a program called Graphical Analysis. Mr. Henderson then took attendance and we started to admire Lindsays very well set up blog post of the day before. Mr. Henderson notices that there is a link to a page with some practice for significant digits. He tells the class that for later blogs if we decided to add a link to our blog we could use that same link for our Delicious assignments.

After we had finished admiring Lindsays

blog it was time to get down to business and take a look at page 13 in our unit packets which had some density practice for us. On the page we

needed to know the formula for density which is, Density = Mass/Volume. It also talks about how the units of density are usually expressed in grams/ml or grams/ cubed centimeters. We then do problems 4 and 5. In problem 4 the density is given as 8.933 g/ cubed cm and the mass is 2.62 g. we have to find the volume of the substance so we use the equation for density and plug in the numbers we know, 8.933 = 2.62/x, in order to solve this problem we will have to use algebra. Start be multiplying both sides by 1/2.62 then we get the answer .293295, this is not the answer because we have not put significant digits into consideration yet. since we

divided we use the same amount of digits of the number with the smallest amount of significant digits which would be 2.62 which has 3. So our final answer for this problem would be .293 cubed cm.

We then go to page 14 of our packets and it is similar to what we do in the computer lab. In the computer lab we plot the volume and mass that is given on page 15 and a graph is made. Then because we have to plot our data from the Dense Cents lab, we plot our information from the Pre 82 and 82 coins and the Post 82 coins.

For homework we had to do 2 webassign assignments, finish labs 5, 6,and 7, because we would be getting them checked on tuesday, and finally we have a unit 1 test on thursday.

Thursday, September 16

We started off today’s class by going over last nights blog, done by Alex P. Mr. H then continued on to talk about the expectations for Lab MM5, which was to make sure you wrote a couple of paragraphs describing the chemical reactions of the substances you tested. Mr. H took a few minutes to review the five pieces of evidence that characterize chemical change, which were evolution of gas, solid being formed, production of heat or light, change in color, and temperature change. Next Mr. H started our lesson on density. We went over the Chapter 1.3 reading sheet (page 21) and took some notes on density in the margin.

NOTES FROM CLASS DISCUSSION:

The big idea was that every substance has a unique set of identifying properties; these properties distinguish the substance from other substances. For example: Water is a colorless substance that boils at 100 degrees C, freezes at 0 degrees C, has a density of 1.0 g/mL and a heat capacity of 4.18 J/gC.

· Intensive vs. Extensive Properties

o Intensive- identifying does not depend on amount

o Extensive- (usually volume and mass) depends on amount

· Chemical Properties: describes how a substance reacts (or not) with other substances

· Physical Properties: describes a substance apart from how it reacts

· Three common physical properties: density, solubility, and color

· DENSITY

o A measure of how tightly that mass is packed into a given volume of space

o Density= mass/volume

o Units: g/cm^3, g/mL, kg/L, kg/mL

After Mr. H explained density, he went through the answers to the 1.3 reading sheet:

1. .A

2. .A. PP, B. CP, C. PP, D. CP

3. .FALSE- The density of a material is specific to that material and not dependent on the amount.

4. .A

5. .D

6. B

7. .C

8. .A

Mr. H noticed that many people didn’t understand how to do number 4, which involves knowledge of significant digits. If you still don’t understand or would like to practice it more then you should go to this website or see packet page 6: http://www.physics.uoguelph.ca/tutorials/sig_fig/SIG_dig.htm

After we did our review and notes, Mr. H explained Lab MM7. The lab was called Dense Cents Lab and the question was “What is the density value of pre- and post-1982 pennies? How do their density values compare? How can the difference be explained?” The purpose was to use a plot of mass vs. volume to determine and compare the density value of pre- and post-1982 pennies and to explain the difference between their densities. First each group separated the pennies into two groups, one with pre-82 and one with post-82 pennies.

Then we measured out 50 mL of water into a graduated cylinder. This was going to be used to find the volume of the pennies, using displacement. Displacement is where you add the objects to the water and difference between the original volume and the new volume is the volume of the object. We massed the pennies in groups of 5 up to 30. After massing each group of 5 we then put them in the graduated cylinder to find the volume. We then divided the volume from the mass of each set to find the density.

Based on the data that we collected, the pre-82 pennies seem to have a higher density. The pre-82 pennies had a total density of 50.095 and the post-82 pennies had a density of 53.545.

Wednesday, September 15

We began today's class by briefly looking at the blog. First, we looked at Konstantine's delayed blog from last Friday (due to technical difficulties, of course) and Katie's blog from last night. Mr. Henderson then proceeded to give us a brief lesson on how to use DropShots with the blog. This link provides the portal to the "Chemistry Classroom" account with the access password being "gbs":
http://www.dropshots.com/chemistryclassroom

While showing the class Katie's blog, Mr. M noticed that Katie had embedded an link with excellent practice into her blog. This reminded him of telling us about the Delicious assignment that we have due on Friday, September 17. He said that Katie's link was a perfect example of what we could use for our assignment. He showed us how to log into the database and how to tag and fill out the form for our links. In order to log into this website, we need a Yahoo account. Mr. H told us that it would be useful to have a Yahoo, Google, or Facebook account because those major corporations would end up taking over many of the smaller companies. Thank you for those wonderful words of wisdom, Mr. H! More thorough directions for Delicious can be found on the hand out we received in class on Monday or on the GBS Chem-Phys website:
http://gbschemphys.com/honchem/index.html

After our tech tutorial, Mr. Henderson asked us to take out our unit packets and turn to page 9. Before beginning the worksheet, he quickly reminded us of the differences between a physical (describing the substance without describing its interaction with other substances) and chemical (describing the substance by how it interacts with other substances) properties. To give us a better idea, he told us he would show us an example of a chemical property of magnesium. He showed us the sample of magnesium - a shiny metal - and turned on the methane flow. He lit the burner (from the bottom up, of course) and began to burn the magnesium. Mr. H told us that magnesium reacted very strongly with oxygen to make magnesium oxide and that we should be prepared to see a very bright light, indicating the reaction. Sure enough, when the magnesium heated up enough, we saw a very bright light. Our experience was similar to this video from Youtube:
http://www.youtube.com/watch?v=Q_LU1EASadU

Mr. H then pulled up an overhead of 4 out of the 5 pieces of evidence of a chemical change. They are: bubbling & production of gas, formation of a solid, heat or light, color changes, or temperature changes. The difference between a heat/light change and a temperature change is that the temperature change is more drastic and long term.

As soon as all the explanation was finished, we began page 9 and the "Verbal Description of Change" section. We attempted to do the section individually and went over the activity together and the answers are as followed: C, P, C, C, C, P, P, C. We had to be on the lookout for the chemical changes we learned about in each of the scenarios order to determine the type of change.

Next, we determined the "Symbolic Description of Change" as a class. If the element remained the same, it was a physical change. If the before and after differed from each other, it was a chemical change. The answers are as followed: P, C, C, P.

To finish the page, we flipped it over and determined the "Visual Depiction of Change at Microscopic Level". We had to be on the lookout for changes in the shape and arrangement of the atoms and molecules. The answers are as followed: C, P, C, P.

Abruptly, Mr. H got up and directed us to the back of the room and under the fume hood. He asked us for two pennies. He took our a large bottle of nitric acid and explained to us what a hazardous chemical it was and how we had to be careful when handling it. Mr. H was going to demo the reaction between copper and this nitric acid. He poured the acid into a flask and diluted it with some water. He dropped one of the pennies in and told us to observe. Meanwhile, he took another flask and filled it with pure nitric acid. He dropped the copper penny into the substance and told us to observe and compare it to the other flask. Immediately, we saw a change of color. The acid went from clear to a gradient green-red. Bright orange gas began spewing out of the top of the beaker. It bubbled and displayed a clear chemical change. The diluted beaker was showing the same changes (minus the color change and significantly less bubbling and gas) at a much slower rate. Mr. H ask Katie to touch the beakers carefully. She told the class they were both very warm, indicating a temperature change. It was very interesting to see the copper penny dissolving and reacting with the acid. The flask with the pure nitric acid and penny looked similar to this photo:

We concluded the class by returning to our seats. Mr. Henderson quickly read us a story about a man whose experience with nitric acid inspired him to keep experimenting with it. With little time left, we were instructed to turn to page 11 and complete the "Verbal Description of Change" and determine the Physical and Chemical properties. The answers are as followed: P, C, C, P, C, P, C, C, P.

Just as the bell was about to ring, Mr. H handed out the quizzes from last week and told us to check our answers and use it as a guide. He told us that tomorrow we could expect a lab about density and that our homework was finishing the 1.2 Webassign and our Delicious assignment.

Friday September 10, 2010

Today's class started off by getting our lab notebooks back. Mr. H graded Labs 1-4, but didn't tell us our grades in our lab notebooks. He told us that he wrote comments and suggestions in most lab books.

Mr. H then had everyone take out their chemistry packets and he went over the question on the bottom of page 6, which was about listing significant numbers when adding, subracting, multiplying, and dividing. He went over significant numbers again and how many to include when adding, subtracting, multiplying, and dividing. The rules are as followed when adding/subrtracting or multiplying/dividing:

Addition/Subraction: The number of decimal places in the result is equal to the number of decimal places in the quantity with the least certainty (i.e., least number of decimal places).

Multiplication/Division: The number of significant figures in the result is the same as that of the quantity with the least number of significant figures.

Mr. H then worked with the class on the first two practice problems to clarify what the rules were saying. He then had us work on the rest of the practice problems by ourselves. After a few minutes of working Mr. H revealed the answers to the class, so everyone was able to check their answers. He answered a few questions from students and then he went to our class's chem blog.

Mr. H went over Hannah's and Neil's blog posts and then gave a few tips on how to make both blogs a bit better for next time.

Mr. H then had the class open up their chemistry packets to the last page to look over today's lab, which was MM6 Conservation of Mass Lab. As the class wrote down the purpose, he explained what we were going to do in today's lab and what to expect. He told the class that since we were going to be dealing with liquids and chemical reactions, that we should wear our safety glasses. He explained to us that we were to find the mass of a flask before the chemical reaction and after, and then compare the differences.

As everone went to their lab stations, they first began by pouring a blue liquid into a flask and then put a testing tube filled with a white substance. Groups then went and measured the flask with all its components as shown below. 

Click to view video.

Groups then returned the their stations, recorded the mass, and then put a cap over the flask, flipped over the flask, and saw the chemical reaction between the white substance and the blue liquid. The result of the chemical reaction was a white solid that formed. Groups then went on to find the mass of the flask with all its components and record their results.

When students finished, they went back to their desks and Mr. H began to pass out scan-trons for our pop quiz. The quiz was only 14 questions, and consisted of the material learned in chapters 1:1-2. The quiz lasted untill the end of class.

Tuesday, September 14

Today we started class with checking our answers for the 1.2 measurements reading sheet (packet pages 19&20). Next, we went over and completed problems 13, 14, 15, and 17 in our unit packets on page 7. These problems were measurements of volume which consists of cubic meters/centimeters, milliliters and liters. We were introduced to a new theory stating that 1 cm cubed=1 mL. That piece of information was key to solving these four problems.

This is my work for the problems above:

After going over and completing those problems on page 7, we were introduced to scientific notation. This can be located on packet page #8. Scientific notation, aslo known as exponential notation, is a way of writing numbers that accommodates values too large or small to be conveniently written in standard decimal notation. On this packet page we converted numbers from standard decimal notation to scientific notation, and then we converted from scientific notation to standard decimal notation. When converting you need to keep in mind that the rule of significant figures still applies. A helpful website for understanding scientific notation is:

http://en.wikipedia.org/wiki/Scientific_notation

When converting, you always write the notation with the FIRST NONZERO NUMBER. (decimal) REST OF SIGNIFICANT FIGURES FOLLOWING *(times) 10 to the Xth power. To determine the exponent (x), you count how many spaces you have to move the decimal (right or left) in order to reach that first nonzero number. If the exponent is positive, that means there is a larger number with numerous zeros after it and you will be moving the decimal point to the left. If the exponent is negative, it would be a very small number and you have to move the decimal point to the right.

If you are trying to convert the numbers from scientific notation to the standard decimal notation, you have to move the decimal place and then fill in zeros. If there is a negative exponent, you will move the decimal point to the left ____ spaces. If there is a positive exponent, you will move the decimal point to the right ___ spaces. Like I said before, significant figures are still in effect for these problems.The last section (3) on page 8 in the unit packet is practice using scientific notation on a calculator. When entering the operations on the calculater, you have to make sure to include all parentheses in order for the answer to come out correct. There is a special "EE" button on the CAS calculators especially for scientific notation. After getting an answer on the calculator, you were then to put those answers back into scientific notation, but more simplified than the original.

The last thing we talked about in class was chemical and physical properties. A chemical property is a property of a substance which describes how the substance interacts (reacts) with another substance. A physical property is a property of a substance which describes the substance without describing its interaction with other substances. This was followed up by a demo lab where Mr. Henderson heated a colorless test tube over a methane burner. The test tube then turned a purplish color and took solid iodine and changed it to a gaseous iodine. This was used during the process of sublimation which includes freezing, melting, boiling, etc.

Here is a link to an interactive website to help you understand the difference between chemical and physical properties:

http://www.teacherbridge.org/public/bhs/teachers/Dana/chemphys.html