Atomic History AND Subatomic Particles Notes


Hey guys so in this video I’m gonna kind
of go over these um the next thing in your packet which are these notes right
here, I just want to show you what it looks like in your packet so that you know
what I’m talking about it’s these kind of notes which I know in
your printouts and even on this it’s a little hard to see some of the text
sorry about that printing in black and white sucks
sometimes but it’s what it is. but this is what I’m gonna be going over but in
like an actual PowerPoint presentation so in case you were wondering what part
of the packet we are in we are gonna be working in you know this kind of
PowerPoint obviously if you look at this you can see that it’s you don’t have to
do anything to it you just have to follow along and so I’m gonna you know
take your words for it and assume that you’re following along with me even
though you don’t have to write anything but this information will be on you know
this unit test in the future whether we’re in school at that point or because
that might be past May 1st I’m not really sure um it depends or you know if
we’re still virtual this information will be on that test and a lot of this
information is what you worked with in the foldable so um you know you should
find it as or a review ok and then the last part of this PowerPoint is gonna be
new stuff that we’re learning well I don’t know if you learned it before we
got before I got there and then we’re gonna be working on this part ok so I
will be doing that with you guys and obviously this is something that you
have to write on so um when I get to this part I’ll give you more
instructions but I’ll have you guys do the same thing you do at the last notes
for you’ll send me a picture of this completed page if you don’t have a
computer too or if you don’t have a printer to print it out on that’s ok
just write it on a piece of notebook paper like you did for the review notes
ok so I’ll get started ok so my face down there so this is like I
said it’s gonna overlap with that fold well you just did that history of atomic
service foldable so we’re gonna talk card about about those scientists today
it’s a little boring but we’ll try to keep it interesting
so this okay so the first person were going to talk about is Democritus
because we’re gonna go in chronological order which we’ll meet which means we’re
gonna go in order of the earliest date to the latest date so we’re gonna start
with Democritus and this was around 400 BC so this is a long time ago way back
in Greece and so he was a Greek philosopher and so philosopher is
someone who just thinks they don’t really figure out like a scientist per
se they just think and they don’t do any experiments or anything but they just
have ideas so that’s exactly what democracies Democritus did is he was the
first person to kind of think about these ideas of atoms or small particles
making things up existing okay so he literally so he thought about atoms
existence and he thought that matter which you know is you know comes in
three forms is composed of tiny indivisible particles called atoms and
atoms the Greek word for that is a Thomas and Thomas actually means cannot
be broken down any further so he thought that atoms were like the smallest thing
you can get we know now that that’s not true but obviously Democritus didn’t do
any experiments so he wouldn’t know that um but he was just thinking that all
matter is made up of these tiny little things but he had no experimental
evidence remember he was just a philosopher so he didn’t do anything to
prove this he was just like this is what I think you can believe it or not okay
so the next person we’re gonna talk about is
excuse me John Dalton and so he actually was a scientist
unlike Democritus because remember Democritus was just a philosopher he
didn’t have any experiments he just kind of sat and thought about things um but
since John Dalton was a scientist all of his theories and you know things that
he’s stating are all supported by evidence that he found mm-hmm he wasn’t
a chemist though he was a meteorologist which is a little weird but he still had
these ideas and he still performed experiments and so what Dalton did is he
had these four major postulates so these four major kind of points to his theory
um it’s a really ugly line but I’m gonna break those down for you so his theory
his first postulate as part of his theory was that all elements are
composed of indivisible particles called atoms and so we know that an element is
something like iron or helium or oxygen and so he said you know every kind of
atom is composed of something that’s indivisible which means you can’t break
it down any further um if the particles called atoms and so heat what he’s
saying is like atoms are the smallest particle same kind of thing as um as
Democritus but obviously like I said he had experimental evidence so he thought
that these individual indivisible particles so I’m gonna put here he
broken down because that’s what he saw he thought that atoms were the smallest
particles just like Democritus the next one of his postulates is that atoms of
the same element are identical the atoms of any one element are different from
those of another and so what this means is you know he’s kind of true in terms
of what we know today um so what he’s saying is that so say we have you know
an oxygen atom all oxygen atoms are going to be the same which is true for
the most part um we might have a little bit of differences because I mean today
we know we have electrons and neutrons and um protons so we know that they
atoms are divisible today and we know that atoms of the same element can be
different in the number of electrons they have and the number of neutrons
they have but for the most part he he’s pretty correct um because he’s just
saying that you know if we have ten oxygen atoms they’re all gonna be the
same but those oxygen atoms are going to be different from something like helium
for those helium helium atoms are all gonna be the same okay so his next
postulate is that atoms of different elements mix or combine in whole number
ratios and so basically what this postulate means is that so
you have you know your atoms of different elements so for example you
have your oxygen and then you have I don’t know carbon okay we know oxygen
and carbon pumped together to form carbon dioxide carbon monoxide stuff
like that um so what he’s saying is that atoms of different elements mix or
combine and whole number ratios he’s saying that like you pretty much won’t
ever see something like half an oxygen atom bonding with a whole carbon atom or
something like that so you’ll never have you know half ratios you’ll never have
half an atom you know bonding to another atom you
won’t have half atoms you know I mean so the example is oxygen combines with
hydrogen to form water in a two-to-one ratio which we know is true because
water looks like you know we have the accident atom and then we have the two
hydrogen atoms so it would be two hydrogen’s so two hydrogens for every
one oxygen and those are whole numbers right there not decimals or anything so
the next postulate and I moved my face up um the next and final postulate is
talking about chemical reactions okay and so we think of chemical reactions as
you know when we mix two things together and you get something new right that’s
the whole basis of a chemical change okay because remember from your test and
those worksheets that you did before I got there
physical changes are just changes to the shape of the molecules they’re changes
to the state stuff like that where the actual substance doesn’t change so
remember my example from the review video is me ripping up a piece of paper
it’s still paper right but it’s just ripped so it changed shape um or like
that question from your test where it was like you know is this a humble or
physical change and it was melting ice down to eventually evaporate it as a gas
and that was a physical change because we’re just a dictating shape no we’re
just changing states of matter and so we could always reverse the process we
could always you know condense that gas and you know that freeze that liquid
back down to ice so we’re not changing what it is it’s still ice and so he’s
talking about chemical reactions which always involve a chemical change right
so this is gonna be where you have new stuff formed you’re actually breaking
bonds and joining bonds and changing what the actual substance is so he says
chemical reactions occur when atoms separate join or rearrange which is
exactly what we talked about when we talked about chemical changes
so remember that little picture I drew where it was like my chemical change was
like wow the circle connected to that square and then we have like the
triangle or whatever that’s a really bad triangle and then that the change is the
breaking of one of these bonds to actually change what it is to change the
actual molecule so this was like oh we still have the circle but now the UM
triangles you know has been broken off of that molecule so now the molecule
itself is different right um sorry this is how I draw my heroes I don’t do that as an arrow um so that’s what he’s
saying so this would be an example of him saying that come for reactions occur
when atoms separate because we just separated um the triangle from that
molecule and so we’re changing it right he’s saying you can also join them okay
so we can join them okay so say we have let’s go to yellow
this time I feel you’re not really able to see him okay so now let’s say we have
the circle and square bonded and then we have the triangle separate and then the
reaction is the joining of these elements well the shapes in our case so
it becomes you know square is bonded to triangle now which is still bonded to
circle so and that would be the joining okay and then rearranging would just be
like moving so do you see how the squares in the middle and the triangle
and the circle on the outside that would be like moving the square the outside
moving like the circle to the middle or something like that so that’s what
rearranging would be so he’s saying that’s what a chemical reaction is it’s
the separating which I already drew the joining which is what I drew here or the
rearranging and then he’s saying that when you’re doing a chemical reaction
the atoms themselves don’t change it’s just you know like the molecules that
change so the atoms themselves so say you have oxygen and carbon again when
you join those together it’ll make you know carbon monoxide gas okay but those
atoms that are still in that carbon monoxide molecule are still carbon and
oxygen it doesn’t change that it’s just now
that they’re bonded together and so that’s your reaction and so he is
corrected in this postulate okay let’s continue so next we have JJ Thompson
which um you have JJ Thompson I’m going to my face for work and what he did is
he did cathode ray tube experiment and so I’m gonna know something really
really quick so when you spelled JJ Thomson’s the name sometimes there’s a P
and I’m gonna go over real quick side sometimes there’s no p3 no P right
there so um either are right I honestly don’t
know if you have repeat and AJ Thompson’s name or not if it’s Thompson
or Thompson I’ve seen both ways in textbooks which is kind of strange but
it is what it is I just want to point that out so if you see like Thompson
versus Thompson like you’re not going crazy both are the same guy okay so
Thompson did the cathode ray tube experiment and so what that is is it’s
this little thing down here and so he had an inert gas an inert gas just means
so inert just means like unreactive of course right but so it an inert gas is
an unreactive gas and so he in addition to that inert gas he had in this little
tube thing here he had two plates made of metal and so one was positively
charged and one was negatively charged and so the reason he’s using an inert
gas Ram the reason he’s using a unreactive gas is because he wants to
make sure that the gas is not gonna react with the positive and negative
metal plates okay he just wants to see where the particles go to he doesn’t
want them to react he just wants to see where the particles you know are
attracted and so what he found what he found is that the particles in the gas
were attracted to the positive plate and what do we know about attraction between
positive and negative we know that opposites attract right so my gosh hmm
so we know the particles must have been negative because opposites attract
so the negative particles were attracted to the positive plate and so that’s what
he found and so then that leads us to our next slide
and it tells us that’s how he discovered the electron because we know electrons
are negatively charged and from this experiment he found that the particles
within the atoms of the inert gas or attracted the positive plate so they
must be negative so that’s how he found these electrons so JJ Thompson is
credited for discovering electrons from his cathode ray tube experiment and so
he believed that atoms were a solid positive sphere and said that’s what
that looks like so just like a circle with a bunch of little electrons just
kind of thrown in there randomly on the sides of it so he thought they were kind
of on the outside and so what they call this is they call it a plum pudding
model umm because like most scientists he is a dead white guy from Europe and
so plum pudding is a European dessert that looks like this it actually looks
really disgusting to me but um that’s what plum pudding looks like so they
permit the plum pudding model because um you know English culture was very
popular back then when this was discovered and they’re like oh this
looks like that pie we make so we’re gonna call it the plum pudding model
because if you look in this all the little plums are scattered throughout
this dough or whatever it is just like how JJ Thompson imagines the electrons
are scattered on the outside of this atom okay so that’s why they call it the
plum pudding model because the electrons are scattered throughout kind of
randomly kind of evenly just like the plum pudding so next we have Ernest
Rutherford and so what Ernest Rutherford is famous for is his gold foil
experiment um and so this is kind of what it looks like I’m gonna hide this
real quick um so what his setup kind of looked like is he had this
cult coated screen and then in the middle of this circular screen
he had this gold this piece of gold foil which is why it’s called the gold foil
experiment and then what he did is he shot high-energy beams of alpha
particles and what alpha particles are your you’re not gonna need to know this
but just you know fun fact I’m alpha powder particles are just they’re just
hydrogen nuclei and so remember the nucleus has you should know this from if
you ever studied atoms before um nuclei have neutrons and protons in them and so
that’s just what an alpha particle is he’s just shooting like hydrogen nuclei
okay so he’s shooting these hydrogen nuclei right and remember nuclei are
just I’m gonna write this down soot it helps you guys kind of understand this and I’m gonna my face yet again when I
come your face so what hydrogen nuclei are like I said nuclei are made up of protons and our protons are positive and neutrons which are
in neutral so I’m putting a zero there cuz they don’t have a charge um so he’s
shooting these alpha particles which are these you know hydrogen nuclei of
protons and neutrons so we know the alpha particles are gonna be kind of
positive because they have positive protons and neutral neutrons which don’t
you know contribute to the charge at all so we’re gonna have an overall positive
particle here right so he’s shooting these positive alpha particles at the
gold gold foil okay and that’s what this is showing you here and he ends up
discovering the nucleus so how um Rutherford found actual nucleus because
I just said he found um the nucleus from his gold foil experiment is so I’m gonna
kind of zoom in on what’s happening here really quick I’m not really quite I’m
going to explain it so this is kind of what it looks like up close and let me
draw for you but bold for like so what I want you to imagine is that okay what’s
happening so this is the gold foil okay so imagine that these are the atoms
within the gold foil okay so the atoms of the gold foil have a nucleus and it
has this electron cloud right so I don’t know if you guys are familiar from
physical science or you know if you did atoms before I got there I’m not really
sure but atoms are made up will we know this now but atoms have a small nucleus
and then it’s mostly made up of these electron clouds which are mostly empty
space and so I’ll kind of get to how Rutherford determined that but so these
are just the atoms of the gold foil okay so he has the gold foil the pure gold
foil and he has angled oil and gold is you yeah I think say you
um and so he has all these a you Adams okay in this gold foil because that’s
what makes up gold and that’s what he’s shooting these alpha particles at okay
so if the alpha particle particles are coming from this direction going this
way towards the gold foil um and remember alpha particle particles are
positive um so if you shooting these positive alpha particles and you know
when when Rutherford is doing this experiment he knows that alpha particles
are positive so he’s seeing what happens if he shoots these positive particles at
the atoms of the gold foil okay and so what he sees is he sees a lot of alpha
particles just going through because we see all this empty space here and so
alpha particles are just gonna go through he also sees a little bit of
deflection and so what this is is remember that opposites attract but same
charges repel okay so if we have a positive alpha particle and we have a
small nucleus what do you think will happen if the alpha particle hits the
small nucleus because we know nuclei are what charged nuclei are positive right
we have at work so nuclei are positive so when we have a positive particle
because I already said it’s positive so we have a positive alpha particle
getting really close to a positive nucleus what do we think is gonna happen
they’re gonna repel right so this is because we have um repulsion and so when
we get really close to this positive nucleus it’s gonna repulse the alpha
particle so the alpha particle is gonna move away from the nucleus and so that’s
why it’s deflected which is like deflection just means it’s you know
moved and the course has changed what Ernest Rutherford also saw was that we
have a rebounding so when he’s hitting the alpha particles or when he’s aiming
the alpha particles at these um atoms of gold he is noticing that sometimes they
rebound okay and so what’s actually happening is now
particles are hitting the positive nucleus and it’s very dense so it can’t
get through and so since the alpha particle cannot get through this very
dense small nucleus it’s just gonna hit it and bounce back
okay so now we’re gonna look at his actual conclusions based on his
observations just you know the basis of science so what he saw is remember I
told you that most alpha particles just went through so most all particles just
went through because like this path so his next observation was that a few
particles were deflected at small angles so right back here that I told you
because of this repulsive force um between positive alpha particles and
positive nuclei that you know when the alpha particles since they’re positive
when they get close to the positive nucleus I’m that repulsion deflects the
path of the alpha particles and because of that he stated that alpha particles
came close to something small and positive because remember positive
positive repel and so that’s how he determined that um the nucleus of the
gold atoms were positive his last observation was that um particles were
very rarely deflected completely back so remember I showed you that sometimes
alpha particle you know just hit straight on to a
nucleus and bounced back and rebounded that’s what this last observation is saying is that he
saw that but it didn’t happen too many times but when it did it didn’t pass
through and so that’s how he knows that the UM the nuclei are very very small um
and very densely packed but also positive so his conclusion that the
particles were deflected at large angles and that happened very rarely is that
you know if something’s very small you’re gonna have a very small
probability of actually hitting it because it’s so small um but when you
know those particles did hit it and he observed that he’s like oh okay well it
must be so dense in that little tiny area that the a particles cannot get
through so that was um Ernest Rutherford’s findings so next we have
Eugene Goldstein and so um I guess you can read that date and so bold scene you
know this is the last particle to be discovered was the proton and he is the
one that discovered that and then um we have James Chadwick Chadwick who
discovered the neutron okay because we have that but we have first we have the
discovery of the electron right AJ so these are discoveries of the subatomic
particles so first we have the electron by it Katie Thompson and we have a nucleus by the nucleus
itself as a whole by Ernest Rutherford and from Eugene Goldstein we have the
discovery of the proton within the nucleus and then Chadwick discovered the
neutron within the nucleus okay and so I already kind of talked about
this but I I said that you know as we went through each one of Elton’s
postulates sermon but that was those four conditions I went through earlier
um so as I went through them I kind of told you this is pretty true this is you
know for the most part on on the right past or I said you know this is not
accurate um so you know with with the discovery of Atomos from the Greek
philosopher Democritus to him saying you know atoms are indivisible and that’s
just what makes it matter to Dalton’s postulate saying you know we have atoms
and that’s the smallest unit of matter same kind of idea we know that that’s
not true because after them came all these discoveries of you know first we
have the electron by Thompson then we have the nucleus by Rutherford then we
have world scene with the proton then we have Chadwick with the neutron within
the nucleus and so we know that the atoms can be broken down so Dalton was
wrong and Democritus was kind of wrong well can you we know that another one of
bail-ins postulates was also wrong so he said that atoms of the same element so
that would be having multiple atoms of an element like oxygen are all the same
so are all exactly the same and so we know today that that’s not
exactly true and so for example we have something called isotopes and isotopes
are something we’ll probably into later but isotopes
long story short are atoms of the same element but they have a different number
of neutrons and so that changes them a little bit but we’ll get into that later
when we talk about isotopes but atoms of the same element are not always exactly
the same and so an example of that would be so if we have two atoms of oxygen I
keep using oxygen because it’s easy oxygens atomic number I think is eight
and so the atomic number remember tells us the number of protons is in that atom
and the only thing that has to remain the same in atoms of the same element is
that the number of protons has to remain constant so the number of protons will
never change for atoms within the same element okay but the number of electrons
can’t change as long as the number of protons stays the same it’s still the
same element but say we have oxygen which has eight protons and in a neutral
atom has eight electrons the number of electrons can change but as long as
those eight protons it’s still oxygen okay so Dalton was also wrong and saying
that all atoms of the same element are identical that’s wrong so now we’re
going to talk a little bit about subatomic particles and just what they
are what charge they have and what mass they have because the mass will be
helpful later on so first particle we um have listed is proton the symbol is just
a p with a little plus so if you ever see me writing really fast and you see a
few of the plus just know that means proton the charge on a proton we already
talked about but it’s positive so it’s plus one and then it’s relative mass
it’s just one okay the next thing we have is Neutron this
symbol for that is just N and there’s no plus or minus next to it because
remember neutrons have a zero charge it doesn’t have a charge
it’s just neutral neutral neutrons and then it’s relative mass is also one the
final particle that we’re gonna talk about is electron and that is going to
be e minus this is something this is an abbreviation I use a ton so if you ever
see me right II – that means electron and the charge
for an electron is minus one and then it’s relative mass is 1 divided by 1840
or for our purposes we’re gonna say that’s relative mass is zero
it weighs basically nothing for our purposes so when we get into talking
about the masses of atoms we’re usually gonna add the number of protons plus the
number of neutrons but we’re not gonna add the number of electrons because
electrons weigh nothing ok so those are three subatomic particles those are
their charges those are their masses and that’s the symbol I might use to write
them the location of the particles so protons I said this already are in the
nucleus neutrons are in the nucleus and then electrons are in the electron cloud
outside the nucleus and energy levels and we’ll get to that later on in this
chapter and I have a ton of practice practice about that so you’ll definitely
feel hopefully comfortable about it but just know protons neutrons nucleus and
electrons are outside of the nucleus in the little cloud last thing in a neutral
atom so this is very important so I’m gonna move my head again so in a neutral
in a neutral atom neutral is when the charges or neutral is when you have a
charge of zero so your charge is zero so when an atom is neutral or zero that
means the number of positive protons has to equal the number of negative
electrons okay so when that happens so for example in oxygen this is my
favorite example apparently you have eight protons and if you have a neutral
atom you need eight positive electrons to make that neutral okay so the last
part this video and I know it’s long I’m very sorry um but this last part of the
video is what you are actually going to be writing down because this my
PowerPoint is green the student version is white so this is what it looks like
in your packet it follows the slides we just finished going over so in your
packet it’s right here and this is what you’re gonna send me a picture of okay
and this is the slides I’m gonna go through so this I’m gonna zoom in on
this so let me can maybe I’m not anyways but so this is the part we’re
about subatomic particles in detail um so the first thing you need to know
about subatomic particles the word subatomic I say very fast but I do want
you to know what exactly it means so sub means smaller than or within an atomic
obviously means atom so if you put it together it means smaller than atom so
you ask what’s smaller than an atom so the parts within the atom that we just
finished talking about so we found out the discoverers discoveries of the
electrons of the nucleus which contains the protons and in the neutrons so those
are the three subatomic particles that there are and we’re gonna kind of talk
about those in detail and if you need to to finish writing you can pause this
part of the video so you can finish writing because I’m not gonna like pause
myself so you can write but if you need to pause pause the YouTube video so we
have several different kinds of particles this is not in your student
version because I think it’s a little bit confusing but this is just telling
you we have matter and we have particles within the matter and those particles
are molecules and atoms and in those atoms we have nuclei and then we have
forces that keep everything together so this is a very fancy table just
saying that we have matter matter is made it by atoms atoms contain nuclei
and electrons and within those parts of the atom what holds them together are
these forces you don’t need to know those forces or anything so don’t um get
overwhelmed so the first we’re going to do is we’re gonna draw an atom okay so
we’re gonna go ahead and I know you have to do this in your in your packet to see
this is where you have to draw the atom just draw everything that I go
through on here so first we have here so first I’m gonna do the nucleus okay and
so I’m gonna make this is the nucleus come on this is gonna be the nucleus the
nucleus goes in the middle for our purposes okay so the nucleus is
gonna go in the middle so you can already draw a little circle inside the
bigger circle and what do we know that we just kind of talked about that’s in
side the nucleus what particles are in it so we have protons inside the nucleus
so I’m just going to throw these little protons in here and then we also have
neutrons these guys in here so what you need to take away from no no don’t move
that what you need to take away from this is that all the protons and
neutrons are inside of the nucleus so continuing the last thing we have to put
on to the diagram here are the little electrons and the electrons go on the
outside circle so I’m gonna move them out here that’s gonna go there so do you
see how I try to place them kind of on the outside circle they sit on the
circle okay not in it not outside of it but I tried to put them on the circle
but of course like the computer is it my best friend right now
um so that is how you draw the atom and so this kind of
but I just did interactively with you but the nucleus is in the middle then
you do the protons then you do the neutrons and then the electrons on the
outside and so what holds the atoms together is called al extra
electrostatic force and so it’s between the protons and electrons and so the
protons and electrons are opposite charges right and so we don’t really
know why the electrons don’t just like float away but we think it’s because of
this electrostatic force um because protons since they’re positive attract
the negative electrons so they won’t go very far okay they’re gonna stay in
their little electron cloud out here and so we note that the charges are equal in
size even though that they are they’re equal in charge the charges are equal um
even though the actual size of the particles is not so we see that the size
of the electron is significantly smaller than the size of the proton it matters
with the weight because remember the weight of the electrons is very small
but the weight of the protons is one same with the neutrons is also one but
the size of the particle doesn’t have anything to do with the charge on it
this is minus 1 and this is and the protons are plus 1 ok and so you need to
know that this electrostatic force pushes you know the electrons so they’re
us far away from each other they possibly can be but it keeps the
electrons close to the nucleus as they can and then the last thing we’re gonna
talk about is what hold or the nuclear force so the nuclear force is going to
be between the protons and neutrons and then it’s x over a short distance so the
nuclear force only applies to the nucleus it does not apply to keeping the
electrons in because it only acts in a short distance it only acts within the
nucleus it doesn’t act over you know the distance from the nucleus to the
electrons that’s what the electrostatic force is
the nuclear force is just acting within the nucleus and then it’s just what is
between the protons and neutrons okay so that’s the part I wanted you to send
me a picture of my laptop is about to die if you can’t see down here so I’m
gonna go charge it you have any questions about this let me know I’ll
give you several days to finish this video I mean obviously if you got to
this point you’re finished so it doesn’t matter at this point but um you have any
questions let me know and we will do practice over it next that’s the next
thing we’re gonna do is practice over this concept okay all right thank you

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