I can see the LIGHT!!!! but its bouncing off my eyeballs....

Its a wave, its a particle, no.......its LIGHT!!!!!!!! (or a unicorn if you're Niki)

So if you hadn't guessed it already this post is going to be all about Light! Yay!!!! This week in Chem we did a Spectra lab.  I other words we looked at different light sources (Some of the sources being low pressure tubes filled with a gas like Nitrogen or Helium that had an electric current run through them) through spectrascopes (Cardboard tubes with a special little plastic film on one end, and a tiny slit on the other.....sounds fancier than it really is.)  When you look at the light through the spectrascope the little slit limits the amount that passes through the tube into the the plastic. The plastic splits the light in to the different wavelengths (ROYBGIV).

White light Spectra through Spectrascope

The different light sources emit different wavelengths. When you look at the light through the spectrascope it is possible to determine the element in the light source based on those wave lengths.
In the above picture is a florescent light bulb as viewed through a Spectrascope. Because it emits white light (all wavelengths combined) you can see bands of all the different spectrums present in the picture. Other light sources emit different frequency's of light.  The different frequencies of light are caused by the electrons in the element being at different energy levels.

Energy levels:
-Bohrs Model---------Rather than having electrons located at fixed points in side an atom they are located within different energy levels (called orbitals in Bohrs model)

Bohrs Model

Electrons are located on the blue rings (they are impossible to locate at specific any time) they orbit the nucleus. When you add energy (in the form of electricity) the electrons jump to another level and back to their original level, producing energy in the form of light waves. The black spots are due to the element not being able to make those specific electron jumps. Today rather than orbitals electrons in a particle model are thought to be in electron clouds.

Cloud Model

In the cloud model the 1s, 2s, 2p, and 3s orbitals are the different energy levels. In the cloud model Electrons exist in probability densities which take on certain shapes, not orbitals.



The only problem with Bohrs model is that the math only worked for Hydrogen. Because of this people began to think that electron were waves. In other words, each electron also has a wave, (Thanks a lot to Louis Victor de Broglie) which can be calculated by the equation below, where h is the Planck Constant, and p is the momentum:

Bohr's Caption

With this formula you can calculate the wavelength of anything, therefor everything has/is a wave. Now your every day objects like a car have such a small wave length (thanks to that equation) that it is not noticeable (more like an object, less like a wave). But when you get down to the amazingly small objects like an electron the wavelengths become bigger, and noticeable (thanks again to that equation).

The Wave Model

So.......In conclusion the wave model is pretty far out there in left field for me (mostly because it a pretty new concept) but, I'm hoping that if I Google stuff repetitively,  and ask questions that I should grasp it before the final...hopefully.

This Week In Chem....(Lame Title Right?)

So this week in Chemistry was a bit of a refresher course in the history of the atom. I know, you're jealous right? Actually I remember that at some point in Intro to Chem I had learned all of key points (Rutherford's Model, Cathode Ray Tubes, Plum Pudding Model, etc...) but promptly forgot it all after the chapter test. The most important points that we cover this week include, the progression of models of the atom (Democritus, Dalton's Atomic Theory, Thomson's Plum Pudding Model, Rutherford's Atomic Model, and Chadwick's revised Atomic Model with the neutron. We also learned how they discovered the sub-atomic particles (Cathode Ray+ Magnet (Electron), the Gold Foil experiments (Protons), Chadwick's discovery (Neutron). The last bit of learning that went on this week involved Atomic Number (# of protons or electrons in an element, what makes and element that element) and Atomic Mass (# of Protons+ # of Neutrons, usually both #'s are equal unless it is an isotope(Element with extra neutrons)). So this all basically sums up the week in Chem, minus the completely off topic discussions that came up during homework time on thursday. I should've probably been doing more homework and less talking but, hey it all worked out...

Separation Techniques Lab

So this last week in Chem we have been doing a Lab on separation techniques... And now that the lab is over we are supposed to write a blog post on what we learned. The first technique that we worked with was filtration. Filtration works by running the mixture through some kind of screen or filter to separate mixtures, like sand from water. Another experiment that was done was separating iron fillings from sand, this was accomplished by using a magnet to pick out all of the fillings.

The experiment that worked I on was Distillation. The way that the experiment worked was that we took a mixture with 5.25g of sugar dissolved in 100ml of water and put it into a distillation apparatus.  The way that the apparatus worked was the water was in a flask on top of a heating element with a rubber stopper and plastic tube in the top of it that connected to another flask sitting 9 inches away on the table. (look at the picture if you don't get it) The water evaporates from flask 1 and the vapor travels through the tube (which was cooled by wet paper towels), condenses and drips down into flask 2. Once the water has all evaporated you are left with a mass of gooey sugar in the bottom flask 1. Once the water is all gone then you should take the sugar off of the heat otherwise you will end up getting a permanent layer of burnt sugar        in the bottom of your flask....which is no fun to clean off. Trust Me.

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Distillation Apparatus

The last lab that we did was a chromatography lab. Chromatography works by having a solvent (water) dissolve ink that is on some kind of a matrix (filter paper). The lighter particles in the the ink are carried farther through the matrix by the water. The heavier particles stay farther back near the original line drawn on the matrix. After the water has traveled through the paper and the ink has separated there is a pretty cool pattern left on the matrix.

Chromatography!