Full transcript
0:00sure great we get these spectrums three
0:02different spectrums they look cool we
0:04learn a lot of information we can figure
0:06out what things are made of but why okay
0:11why do these different spectrums exist
0:12and we're actually gonna have to look at
0:14the structure of the atom like this
0:16slide says because that accounts for the
0:19different types of spectrums we get or
0:21at least we're gonna see that in a
0:22second so let's start looking at the
0:24atom and realistically a good place to
0:28start is looking at Rutherford's
0:30research because he was one of the early
0:32ones to try and figure out what was
0:35going on with our atoms and actually he
0:38had this neat experiment he took this
0:40very very thin gold foil very very thin
0:43sheet of gold foil and what he did is
0:47sent a beam of charged particles at it
0:50and the weird thing is and these were
0:54positively charged particles so things
0:58that were positively charged overall had
1:01a positive charge well what he found is
1:05some of them bounced back even though he
1:08was sending in this ad to this
1:09incredibly thin sheet where they should
1:11just pass through without a real big
1:13problem some of them were bouncing back
1:15and from this he was able to predict
1:19that our atoms must have a relatively
1:24large core of positive charge because
1:27these positive charge were hitting other
1:29positive charges and being reflected
1:32back because we have to remember plot
1:34like like charges repel unlike charges
1:38attract so what do you I pod size is
1:40there must be this core of positive
1:42charge that some of the particles were
1:44reflecting back of course a lot of the
1:47charges worked so he ended up realizing
1:49this must be well as much as this
1:51relatively large core for the atom it's
1:54still very small
1:56most of the atom he realized was empty
1:59space and he also realized that this
2:02atom was overall neutral so as much as
2:08we had a positive core there must be new
2:10negative charges surrounding it or
2:13that's what he theorized native charges
2:16surrounding it and if we were to plot
2:20this out we'd see hydrogen would be the
2:23simplest where we have a proton in the
2:25core and electron orbiting it now it is
2:29worth noting that this model is actually
2:32not correct not correct we have more
2:37complicated ways of thinking and
2:38understanding the atom now but for the
2:40purposes of this class this is gonna be
2:42a very good way of thinking about it and
2:44it's close enough for our purposes so
2:46we're gonna use this idea but
2:49technically it's more that this
2:51electrons in a cloud around the proton
2:54but for our purposes we're gonna stick
2:57with this we also think of heavier
3:00elements where there is more than one
3:03proton in the middle and these would
3:05again be balanced by an equal number of
3:07electrons if we have a overall neutral
3:09element but with heavier elements beyond
3:12hydrogen we also start adding so-called
3:15neutrons neutrons which have a neutral
3:19charge very appropriate named Neutron
3:21neutral basically the same word almost
3:23so you think neutrons are neutral and
3:26for neutral P for positive for protons
3:29and electrons just the remaining ones
3:31have to be negative to balance
3:32everything out so this is the basic
3:36model and as we get to progressively
3:38heavier elements we just have more
3:39protons more neutrons more electrons and
3:42maybe more and more shells of electrons
3:47but the thing was that this model even
3:52at the time was pretty good but they
3:55figured you know what it didn't make the
3:57most sense because why aren't the
3:59electrons spinning closer and closer and
4:02losing energy and eventually collapsing
4:05in and they realized that that should
4:07probably be the case these electrons
4:09should be losing energy and spiraling
4:11towards proton and it should collapse
4:13within a fraction of a second but
4:15clearly that wasn't the case because
4:17then we wouldn't exist if that was
4:19happening well nothing would actually
4:22exist none of our matter so what was
4:26going on why
4:27these electrons collapsing to the proton
4:30well a guy named Bohr came out with a
4:34very strange idea and what he said was
4:38that these electrons must orbit only at
4:42very certain distances from the proton
4:45at very certain energy levels and I
4:50think it only orbit at those energy
4:51levels none others and this was a
4:55fundamental important idea so let's take
4:58a look at this image right here what we
5:00see is that maybe the electrons could
5:02orbit at this circle and we're assuming
5:06by the way that the core is in here the
5:08proton core is in the very middle but
5:10we're ignoring it so if we had the very
5:12center in orbit there or at this
5:17distance or at this distance but nowhere
5:20in between and each of these is a
5:24different amount of energy apart from
5:27each other so this might be a very set
5:32energy this would be a different energy
5:34and ideas that the electrons can only
5:36orbit at these very set points no others
5:40and actually what we find is each and
5:42every single atom each element has its
5:45own energy levels so its own orbits that
5:49the electrons are on but these electrons
5:55can jump to higher energy levels they
5:59can be excited
6:00something can give them energy so that
6:03they jump to a higher energy level the
6:05thing is it has to have exactly the
6:08right amount of energy and so I'm gonna
6:11make up some numbers for a second and
6:12bear with me the actual numbers don't
6:14matter the idea matters let's say an
6:16electron was right here well if
6:20something came in so right here if
6:24something came in and gave it exactly
6:26the right amount of energy it could jump
6:28up to here or to here or it all the way
6:30up to there but only if it was given the
6:33exact amount of energy so let's say this
6:35takes I don't know 1.5 joules which is
6:39not at all an accurate number
6:40for what we're talking about but who
6:42cares maybe this is one point five
6:44joules to jump from here to there if
6:46something came in with one point six
6:48joules you'll just pass on by something
6:51passes by with one point four nope no
6:53good has to be exactly one point five
6:56joules now of course what might this
6:59thing of giving energy be how about a
7:02photon a photon of light light coming in
7:06has very certain energies remember
7:09especially thinking about it as a
7:11particle a photon of light has a very
7:13certain amount of energy if one came in
7:15with that 1.5 joules number I made up it
7:18would cause the electron to jump from
7:20one orbit to the higher one of course if
7:25it passed by with one point five one
7:26nope no good has to be exact and and it
7:32also could be that I mean this jump here
7:34is 3 joules
7:35well if there was something with 3
7:37joules then that one might get absorbed
7:39and jump to a higher energy level the
7:42idea is it has to be exactly the right
7:45amount of energy to make it jump and so
7:48it might be because of again light
7:51coming in also could be two atoms
7:53colliding together and causing the
7:56electron to jump but the idea is the
7:59right amount of energy comes in the
8:01electron can jump to a higher energy
8:03level absorbing that energy in the
8:05process so that photon of light comes in
8:09with 1.5 joules the electron absorbs it
8:12jumps to a higher energy level absorb
8:16that photon and jumps