Thursday, October 18, 2012

Atomic Structure...an update

             The thing we have been focusing on the most in Chemistry is Atomic Structure. I have found that this is  a lot more complex than I thought it was.
We have been going over many concepts that have to do with Atomic Structure, the first one is light-why it is the way it is and how it is the way it is. Analysis of light emitted by certain elements showed that and element's chemical behavior is related to the arrangement of electrons in its atoms. That is why it is so important to discuss light.
First, there are two natures of light: Wave Nature and Particle Nature.
Wave nature of light can be described by many different characteristics like...

  • Wavelength-The shortest distance between equivalent points on a continuous wave. Usually expressed in meters, centimeters, or nanometers
  • Frequency-the number of waves that pass a give point per second. Measure in Hz (1 Hz=one wave per second)
  • Amplitude-The wave's height from the origin to a crest, or from the origin to a trough.
  • Speed- ALL electromagnetic waves, including visible light, travel at a speed of 3.00 x 10^8 m/s.

Particle nature of light:
The Particle Nature of Light is important because it explains why heated objects emit only certain frequencies of light at a give temperature, it also explains why some metals emit electrons when certain colors of light with a specific frequency shines on them. This is something that the wave nature of light can't do. 

This is a Concept Map I created to further explain the information I have learned about the two different natures of light!


Notes from the light Spectra lab
As you can see this is a picture of the notes and drawings I took when we did the light spectrum lab. During the lab we used spectrascopes to look at different forms of light...I found it really interesting the way the spectrums appeared for the different types of light.
Sunlight passing through a prism is separated in to a continuous spectrum of colors. You can see this in my drawing to the left, in our lab we looked at an incandescent light bulb to see the spectrum.

We also looked at an absorption spectrum. We looked at green light (a glass full of green water in front of the light) and it changed the spectrum. The green was absorbed and there were some oranges and reds. We then looked at red light (a glass full of red water in front of the light) and found that the red dye blocked the red part of the spectrum and there were many blue and greens. Green plants are green because they mostly use red light...the reds are absorbed and then the green color is what is reflected!
Green Plants mostly use Red Light
The Electromagnetic Spectrum includes all forms of  electromagnetic radiation and shows the differences in their frequencies and wavelengths.






An Atomic Emission Spectrum of an element is the set of frequencies of the electromagnetic waves emitted by atoms of the element.
For example...Neon, if you look at my drawings of the spectrums above, Neon's spectrum consists of several individual lines of color, not a continuous range of colors as seen in the Visible Spectrum. Each element's atomic emission spectrum is unique. 




Different Models and Theories in Atomic Structure:
Bohr Model of the Atom-Taking from the ideas Einstein and Planck had on quantized energy.
He proposed that the HYDROGEN atom has only certain allowable energy states. The Ground State is the lowest allowable energy state of an atom. Bohr suggested that the single electron in a hydrogen atom will move around the nucleus in only certain allowed circular orbits.

From the Glencoe Chemistry Book
THE GROUND-STATE ELECTRON CONFIGURATIONS
An atom's electron configuration is the arrangement of electrons in an atom.

The aufbau principle: States that each electrons occupies the lowest energy orbital available.
Features of the aufbau diagram:

  • All orbitals related to an energy sublevel are of equal energy. 
  • In a multi-electron atom, the energy sublevels within a principal energy have different energies.
  • In order of increasing energy, the sequence of energy sublevels within a principal energy level is s, p, d, and f.
The PAULI EXCLUSION PRINCIPLE:
States that a maximum of two electrons may occupy a single atomic orbital, but only if the electrons have opposite spins.
HUND'S RULE
States that single electrons with the same spin MUST occupy each equal-energy orbital before addtional electrons with opposite spins can occupy the same orbitals.

Also taken from the Glencoe Chemistry Book
This diagram shows the order in which orbitals are usually filled.



Obviously there was a lot of information in this post, it is just a basic overview on the world of Atomic Structure, I know that I am definitely still learning more, but I think this post really shows the beginnings of what I am learning about in Chemistry, and I look forward to learning much more in the second quarter!

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