So when scientific
models are developed scientists do a
variety of experiments which then
culminate and support the different
models.  We start with the atom..the
model we started with was Dalton's
model of the atom, and then as the
subatomic particles and they did more
experiments that was modified and we got
to JJ Thomson's model, which remember was
the plum pudding (model) and then they did the
gold foil experiment and Rutherford's
model came to be more accepted  (a
modern-day) the nuclear atom where we
have the protons in the nucleus and the
electrons outside of the nucleus
Remember it wasn't Rutherford that
discovered the neutrons there (in the nucleus).
We have this modern atomic nuclear model...What Rutherford's model didn't do
was explain the location of the
electrons in relationship to the atoms
on the periodic table.  We knew the
electrons were outside the nucleus, we
knew some of their characteristics, but we didn't have a model that would
help us understand what we see in in the
relationship to the organization of the
atoms on the periodic table.  So in order
to kind of begin to understand the
electrons we have to take a step back
and understand just a wee bit about
electromagnetic radiation.
Now electromagnetic radiation, which can
also be abbreviated EMR, it is one way that energy travels through space.
And in this course we're just kind of
gleaning a few of the words that will
help us understand a little bit about
the electrons. But electromagnetic
radiation could be an entire course in
and of itself and really to completely
understand the electrons we would have
to investigate it a little bit more and
if you take chemistry one
you will begin that a little bit more
in-depth investigation of
electromagnetic radiation. But for us
we're going to take a few of
its characteristics and understand how
it relates to what we see and how we can
understand the electrons and their
location a little bit better. So I
already mentioned that electromagnetic
radiation is one way that energy travels
through space and what it all does...let
me tell you some of the forms (of EMR)... I have the
spectrum in a couple slides but it's
things like x-rays, and visible light, and
gamma rays, and ultraviolet light, and so
it's these different forms of energy.
One thing they have in common is that
they travel they show wave-like behavior,
so if you think of the ocean, which also
has wave-like behavior, that is how this
radiation travels through space. Another
thing that these types of
electromagnetic radiation have in common
is that in a vacuum it all travels at
the speed of light, which is 3.00 x 10^8 m/s
Now a couple of the basic characteristics of
electromagnetic radiation that we look
at are wavelength, which is given the
symbol of lambda (it is a Greek letter) What
I'm saying is "lambda" and wavelength is
the distance between the consecutive
peaks, (so) a peak is the top so
consecutive would mean one after the
other.  So if I measured that distance ,you
see here I get lambda. You could also
measure from what's called a trough,
that would also be the same distance. So
that's the wavelength.  We also have
frequency which is the Greek letter nu
and frequency tells you how many waves
pass a particular point per second. Then
we have the speed, which tells you how
fast it's traveling through light, and
remember in a vacuum all (light travels
at the) I mean all energy travels at the
speed of light
So here is the electromagnetic spectrum
and it (the diagram) gives you an idea. So there's this
evidence of this wave-like nature, how a
this energy travels through space
like a wave in tiny packets, and we can
relate that to the energy of the little
packets of light which we call a photon.
And the energy of that photon, "E" here is energy
is related to, this is a constant,
it's named after a person, it is called
Planck's constant (h).  We have this frequency
on the top here and then here's lambda
that's the wavelength (I can't write wavelength here), so that is the wavelength of
the light so looking here we can see
that energy is inversely related to
wavelength because the wavelength is in
the denominator and what that means is
the longer, so a long wavelength means
you're going to have a low energy
because they're opposite, so the bigger
the wavelength gets, the smaller the
energy gets or you could rephrase it in
the other way and we could say a shorter
wavelength would mean we have a high
energy.  So let's look at our
electromagnetic spectrum. So the
wavelengths are down here at the bottom (circled on right),
you can see here, and it tells us that
it's in meters, so this is 10^-16 (left)
and this over here is 10^6 (right). So this end (left) has a shorter
wavelength, so gamma rays this end (left) has a
higher energy, and
is 10^6 (right), these radio waves, these
have a lower energy.  So the energy of the
light relates to its wavelength.  It's
also kind of cool if you look at the
visible spectrum you see that different
colors of light will have different
energy.
Now this spectra here is in nanometers,
this part of the spectra, but this end (left)
this has a shorter wavelength so this
the purple light has higher energy and
then compared to red light which would
have lower energy.  So the colors of the
light actually can give us insight into
the energy of the the radiation itself.
Now I don't know if you've ever heard of
ROYGBIV but that is a way that I
remember (now this spectra is a written
the opposite) but Roy "R" red, "O" orange, "Y"yellow, "G" green, "B" blue, "I" indigo, "V" violet. So
that is a way... I think of it as a name...
that I can remember the color of the
rainbow of our visible light spectrum.
Red having the lowest energy going
through violet which has the highest
energy. Now energy, we can treat this with
its wave-like behavior, but it also comes
out in little packets we call photons. So
when we think about light do we treat it
like a wave because it has a wave motion?
Or do we treat it like a particle
because it has these little packets of
light called photons? Well scientists
have agreed to use both, it's called wave-
particle duality, to explore or explain
light. That would make the best model if
we can
use both and we're going to see that
that duality helps us understand what
electrons do as well
