# [CH 301] - Midterm Exam Guide - Everything you need to know! (18 pages long)

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7 Feb 2017
School
Department
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UT-Austin
CH 301
MIDTERM EXAM
STUDY GUIDE
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Day 1: 20/1/17 Rutherford atom, Wave properties, Electromagnetic radiation, Blackbody
Rutherford Atom: central core containing most of
the mass and half of the charge of the atom
surrounded by cloud of e-
Limitations include…
Did Not explain why elements have
different protes
Did Not explain how chemical
bonding occurred
It didn't explain storichmetery
energy and slowly plummeted into
the core
Did Not explain why different atoms of
different give off light character when burned or when electricy passed through them
(atomic emission)
Wave properties
Wavelength () distance between 2 consecutive peaks or troughs in a wave (meters)
Larger wavelength = smaller frequency inverse realtsnipip
v = constant m/s or ms-1 (speed or velocity)
Frequency (v) # waves/ 1
sec or sec-1 in Hertz (Hz)
Light Waves: both electric
When passed through a
prism makes rainbow
ROYGBIV (only cause our
eyes only pick up this
Shorter wavelength
= high
frequency/high
energy
Long wavelength =
low frequency / low
energy
Reading music is very unsafe for xylophones and glockenspiels (pneumonic)
Speed of light (c) is a constant in any specific medium
C = 2.9979249 x 108 ms-1 in ALEKS use C button
   3.0 x 108 ms-1
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Light travels through water at a different speed than air
Example Problem: = 520 nm, what is the frequency in MHz
   c = 3 x 108ms-1
1) Rearrange formula v = c/
2) Metric needs to be in m v = (3.00 x 108 ms-1) / (520 x 10-9 m)
3) Plug in v = 5.77 x 1014 s-1
4) Change units v = 5.77 x 1016 Hz
5) Change to MHz v = 5.77 x 108 x 106 Hz
V = 5.77 x 108 MHz
Why do things look a particular colour?
The wavelengths we see are reflected and everything else is absorbed
Pass electricity through gas and glows a color
If you change the temperature (heat it up) it will change color
Metal goes red blue white hot (UV)
Black body theoriginal: absorbs all wavelengths of light and reflects nothing: therefor it
appear black
If you heat that object the ration it would emit is independent of what the object is
made of or ist surround but only depend on temperature
Gives light off of different color
As temp the intensity and the peak wavelength of hte light
Brighter and shorter wavelength
There is a drop in intensity at low wavelengths
Ultraviolet catastrophe= physicists predicted the impossible so Planck made a theory
that would explain it
E = nhv
Change in energy of the stem when it emits light energy E, n is an inter, v
frequency, and h is now planck’s constant
h= 6.62607004 × 10-34 m2 kg s-1
Energy can only change by integer multiples (not any possible value) only
multiple of hv (quantization)
Photoelectric Effect
Bell jar pumps out all the air and a metal anode (+) electrode
If you shine light onto the metal surface the e- are being ejected
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