Wednesday, November 10, 2010

Just a Memo

I made a Prezi about the periodic table. It has alot of great information! Check it out!
please just watch the show rather than editting any of the work. thank you! ENJOY! :)

Tuesday, November 9, 2010

Conductivity Lab

            We recently have been learning about atoms and we are talking about their break down or build up into ions. Certain atoms of substances are much more likely to become ions than others. For example, Sodium has an electron configuration of 1s22s22p63s1. Because of this, Sodium is often found in its ion form Na+, this means that often sodium looses an electron to become stable like neon. This makes it a pseudo-noble gas with the configuration of 1s22s22p6. This was just one example and we figured if sodium was likely to make ions then so were other elements. We constructed & preformed a conductivity lab. In this lab we tested 8 different substances dissolved in distilled water with the purpose of finding out which solution held a greater concentration of ions. For each solution we would record our prediction of how high the ion concentration would be ranging from none to very high. From here we tested with a simple, store-bought, battery-powered, ion concentration detector. This only detected from none-very high, it gave no numbers & no precise measurements. After we tested all of these with this conductivity tester, we tested these substances with the conductivity probe. This probe can accurately measure these solutions to give us even a better idea of how highly concentrated each solution was. 
            Here is the data we collected:
Substance                 Prediction            result w/ tester              result w/ probe (uS/cm2)
Methanol                      high                     very high                            249.2
Calcium Chloride       medium                  very high                            246.6
Albumin                     medium                  very high                            248.7
Cupric Oxide               low                         low                                   22.4
Ammonium Sulfate    very high                  very high                            249.3
Glucose/ Starch            low                         low                                   35.0
Citric Acid                   high                         high                                 249.3
Sugar Water                 low                         low                                   16.1

            From this data we can conclude that certain dissolved substances such as Ammonium Sulfate and Citric Acid have a much higher concentration of ions than substances like Sugar Water and Gluscose. In some cases, substances wouldnt always dissolve well in the water to give a very accurate concentration reading (Ex: Cupric Oxide). Overall, we learned that many dissolved substances have concentrations of ions whether high or low.  

Wednesday, October 6, 2010

Line Spectra Lab

Picture of white light with
continuous light spectrum.
        We did a lab called the Line Spectra Lab. In this lab we did multiple experiments that showed us and helped us to understand the 3 major different types of light spectra. Those include the: continuous spectrum, absorption spectrum, and emission line spectrum.
        The first type of spectrum we experimented with was continuous. White light, such as sunlight, will always have a continuous spectrum if it is incandescent. This means that within this spectrum the colors red, orange, yellow, green, blue, indigo, and purple will always show when the pure light is broken down. Another way to say it is, all of these colors combine to form white light and when seen with a spectroscope the colors appear in a continuous row.
        The second type of spectrum we viewed was absorption. We viewed this by putting a bottle of red colored water up against a white light. We used our spectroscopes to peer through the bottle. When I looked through my spectroscope I noticed that I saw the light being transmitted but not the light that being absorbed. From this I determined that that red light absorbs blue light because I saw a lot of red and the green/blue lights had disappeared.  In the absorption spectrum colors continue, but some may be missing.

Light Spectrum seen for the
fluorescent overhead light
        Finally, we took a look at the emission spectrum. The first thing we looked at was the overhead fluorescent light. This is a type of white light but due to the fluorescent bulb the spectrum showed up in bars of all the colors (ROYGBIV). After this we got a little more complex. We used a spectrum electric power supply to give high voltage to tubes of enclosed gasses. Each gas when lit appeared a different color to the naked eye and produced different wavelengths of colors that we saw as defined colored lines in our spectroscope. This experiment deals with electrons bouncing between energy levels of the atoms. If we would have gotten more in depth with it we could have calculated the energy of the waves based off of Plank's Constant and the frequency (E=hf). The first gas we looked at was Hydrogen. Hydrogen appeared purple to the naked eye, but when seen through the spectroscope i saw a bright red, a cyan, and a purple. One thing i noticed, which was true for all the gases we looked at, was that in between the colors we were seeing black. At first i was wondering what would cause the black, then i realized that we didn't see those colors because their wavelengths weren't visible. Their wavelengths weren't visible because they are not a possible jump for the electrons to make between the energy levels. The wavelengths that were visible, were visible because when the electron was dropping back down to the ground state it shows off the color depending on the frequency. Once i had this concept down, we looked at six different types of gases (not including hydrogen, which we had already seen) and made observations about the different colors emitted. Helium showed orange to the naked eye, but when seen through the spectroscope i saw lines of faint red, bright orange, dark green, and purple. Nitrogen appeared orange with a bit of purple at the end points of the tube, but when seen in the scope it had lines of bright red, a little yellow, green, and purple (these lines were blended a bit more than most of the other gases). Next, was Mercury. To the naked eye it appeared a light blue, but it emitted lines of very faint red, light orange, bright green, and purple. Neon came next and looks bright red to the eye, but the scope showed a lot of very bright red streaks with a orange and yellow streak as well. Dark green and dark purple were also seen, but very very faintly. Then, iodine was viewed. Iodine appeared white to the naked eye and with the specroscope I saw very bright colors red-green sort of blended together and then two very defined lines of blue and purple. Finally we looked at Argon. Argon was purple to the naked eye, but when seen through the spectroscope I was a very faint red orange, a light green, dark green, and purple line (no lines were very intense in this gas).

        All in all, these experiments that we did in this lab helped us to understand the 3 major different types of light spectra. Again, those include the: continuous spectrum, absorption spectrum, and emission line spectrum. Continuous light deals with plain white light and has a continuous streak of colors when seen with a spectroscope. The absorption spectrum has a colored light in front of white light & so when seen with a spectroscope you only see the colors that are transmitted, not absorbed. Finally, with the emission spectrum you see the break down of bars of define colors emitted, in our case, by the different gases. I learned a lot from these experiments and now truly understand the basics of each type of light spectra. For anyone else out there trying to learn the same material, I hope this helps to explain the types of light spectrums better & gives you some mental pictures to work with in order to comprehend this lab a bit easier. : )

Saturday, September 18, 2010

Chapter 4 Concept Review


        I feel that I understood a lot of the information and material that we covered throughout Chapter 4 "The Structure of the Atom". First we started off learning about the philosophers. Many of the early philosophers were Greek including: Democritus, Aristotle, and Dalton. Democritus's ideas were definitely a beginning point. He believed different kinds of atoms had different size and shape, different properties of matter were due to different atoms movements, and matter was composed of empty space through which atoms traveled. This ideas were rejected by Aristotle who didn't agree that empty space "nothingness" could exist. Later on Dalton created his atomic theory. He said all matter was composed of extremely small particles, all atoms were identical, atoms couldn't be created, divided, or destroyed, and in chemical reactions atoms combine, separate,or rearrange. These ideas I understood very well. I also see how the theories have changed over the years with advancements in knowledge & technology. One thing I'm having a hard time grasping is how small an atom really is. In our books it gives an example: In 2000, the world population was estimated at 6 billion. Atoms in a penny is 5 billion times as many atoms in a copper penny than humans in the world! That is a hard concept to grasp!
         I really liked the hands on work with the Cathode Ray Experiment. It was easy to see how the Cathode Ray travels to the Anode side of the tube. I understand how if there were magnetised plates on both sides of the tube electrons could have easily been discovered. From here, Millikan discovered the mass of an electron & that just goes to show me how strong these particles are. They are 1/1840 the mass of a hydrogen atom. If one electron is equal to one proton that just shows its strength when their masses are compared. Then, came Rutherford's discovery of the nucleus. It makes sense how the nucleus was discovered because the alpha particles all went through except where they were deflected by the nucleus. This led to the theory of the nucleus being positive which was later turned into the nucleus is a mix of protons & neutrons. I definitely understand how all the particles work. I understand their mass, placement, charge, & importance to every atom.

        Atomic number, mass number, and average atomic mass number make sense to me. Atomic number is the number of protons a atom has along with the number of electrons it has. Mass number is the total number of protons plus neutrons in an elements nucleus. Average atomic mass number makes sense to me, but it is not quite as clear as the other two yet. I understand how it works & I can do the problems fine, but my mind is still learning to process it. Average atomic mass number is a weighted average mass of the isotopes of that element. Isotopes are when the same element has the same atomic #, but a different mass # because it has more neutrons in its nucleus. I can figure out any of these numbers or any element if given the correct information. I understand all the parts of an atom & I feel very confident in the material I learned throughout Chapter 4.

Thursday, September 9, 2010

Separation Techniques

      Our chemistry class had a few days where we did a separation lab. We focused on separation, distillation. filtration, chromatography, and magnetism. My group did a project where we had a mixture of salt, sand, and iron fillings. First, we used a magnet to separate the iron fillings from the sand and salt (magnetism). We went through our mixture multiple times to make sure that we had all the iron we could collect & all the sand & salt was separate from the iron in the original container. From here we took our salt and sand mixture & added warm water to separate them. We knew salt was soluble so that was one way we could separate our mixture. Then we used filtration paper to separate the salt water from the sand (filtration). This caught the sand & let the salt water into another pan where it was its own mixture. We let our sand dry & our iron was separate too. If we wanted to separate and time had allowed we would have followed through with a distillation process to extract the salt from the water. Then we would have completely had 3 separated substances. Obviously, we lost some countable mass due to moving & touching our mixtures, but if this was done in a closed lab none of the mass would be lost because the law of conservation of mass.
     Another lab we did was on chromatography. Chromatography separates mixtures due to their absorbency. We used water to separate different types of ink into different colors due to their absorbency. These showed up as water absorbed up a paper towel & into filter paper onto the different inks. Some inks spread and others did not.
     A few other techniques that were used by different groups included distillation and separation. Distillation is a process of extracting  substances from a mixture (physical). Heat boils water or a mixture & some properties of this mixture are carried over to the other flask through a tube. In the tube it condenses the mixture with cooler air and the newly distilled product is in the receiving flask. Separation is simple. Separation is completely physical change & all that happens is two object such as rocks & sand are moved into two separate piles without much hard work.
     These are some different types of techniques to separate mixtures that we worked with in my chemistry class. Hopefully I explained myself well.. if you have any questions just ask. :)