Understanding Atomic Structure: Protons, Electrons, and Electron Configuration

[Music] [Music] in the previous video we discovered that

all the atoms in the periodic table are made from just three kinds of particles protons electrons and

neutrons the whole world in fact amazing we know that the heavy protons and neutrons live in the atom's Center

called the nucleus the proton carries a positive electric charge and the neutron is

neutral the light electrons whiz around the outside of the nucleus and Trace out the shape of a fuzzy

ball they carry a negative electric charge we can show the electrons moving but it will be easier to keep them still

in this video we can still learn important things about atoms by simplifying the

real picture let's pretend we have a pile of each of these particles and then build

some atoms from scratch what's the simplest and lightest atom you can think of it must be the one

with an atomic number of one did I hear you say hydrogen it makes sense that this atom is made by

using just one proton how many electrons does a hydrogen atom

need have you notice that stuff around us is not electrically charged most of the time you don't go around with your

hair standing on end from static electricity that means that atoms are overall neutral so that the positive

charge of the proton must be exactly cancelled by the negative charge of an electron and just one

electron the number of protons and electrons must be the same a hydrogen atom has one proton and

one electron the number of protons equals the number of electrons and this is true

for all atoms [Music] [Music]

[Music] what's the next atom on the periodic table

helium to make a helium atom requires two protons and how many electrons two we've just learned

that two two pluses and two minuses overall neutral but we have a problem

Houston the two protons in the nucleus both carry the same charge why is this a

problem they will repel each other so the nucleus will fly apart this is where neutrons come in

handy neutrons provide some extra glue to hold the nucleus together there's an extra attractive

force that belongs in the nucleus called the strong nuclear force that works only between nuclear

particles without this Force the nucleus would disintegrate who

Again by the way they won't tell you about the strong nuclear force until you get to University so this is a kind of

trailer for you a hydrogen atom doesn't need a neutron

why it has only one proton in its nucleus so it won't fuel any repulsive forces by nearby

protons hydrogen is the only atom that can do this all other atoms must have neutrons in their nucleus to keep it

together but from now on we're going to ignore the neutrons in building our atoms to make our video easier to follow

let's remember though that neutrons are found in all atoms that have more than one

proton how do we make the third atom lithium how about with three protons and three

electrons that's correct but we've got another problem Houston electrons live in shells that are wrapped around the

nucleus and the first shell can take only two electrons before it becomes full so lithium has too many electrons

to squeeze them all into the first shell luckily there are plenty of shells available so after two electrons fill

the first shell the extra electron can go into the next Shell this second shell is bigger than

the first shell and can take up to eight electrons this is like a strange hotel that has only two beds on its first

floor so after two guests are booked in extra guests have to be sent to the higher floor

the hotel second floor has eight beds and so after the next eight guests book in this floor is also full

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a lithium atom has three protons in its nucleus two electrons in its first shell and one electron in its second

shell the number of electrons in each shell is incredibly important because it affects the properties of the element

and how it will behave in the world for example lithium is a metal because it has a single electron in its

outer shell we will explain how this happens later the number of electrons in each

shell of an atom is called its electron configuration you should ask your parents if they know what electron

configuration means they're really cool words to learn the electron configuration of

lithium is two electrons in the first shell and one electron in the second shell or sometimes scientists just write

2 comma 1 for short we're on a roll here what is atom number four and how

many protons and electrons does it have and where do they live did you say berum with four protons

and four electrons with all four protons living in its nucleus two electrons in its

first shell and two in its second shell if so you can move to grade 11 in high

school bur's electron configuration is 2 comma 2 two electrons in the first shell and two electrons in the second

shell next atom is number five Boron it has five protons and five electrons two electrons in its first

shell and three electrons in its second shell it's electron configuration is 2A 3 then number six carbon six protons and

six electrons its electron configuration is 2

4 do you notice a pattern here the number of the atom it's atomic number is always the same as the number

of protons in its nucleus earlier we learned that atomic number meant the place of an atom in the list

of atoms from the lightest to the heaviest when scientists discovered these subatomic particles they realized

that atomic number was also exactly equal to the number of protons in the nucleus it means that an atom's identity

that is whether it is hydrogen or aluminium or gold depends only on how many many protons are in its

nucleus the atomic number of an atom is equal to the number of protons in its [Music]

[Music] nucleus we could have defined the atomic number as the number of electrons

as this is the same as the number of protons in an atom however electrons can sometimes be

swiped off the outside shell of an atom or an atom May grab an extra electron or two so this number of electrons can vary

from time to time protons live in the nucleus which is locked away from the outside world

and their numbers don't vary usually this is a better definition let's use up the rest of our

protons and electrons number seven nitrogen seven protons and seven

electrons electron configuration 25 two electrons in the first shell and five in the second

shell number eight oxygen eight protons and eight electrons electron conf figuration 2

six two electrons in the first shell and six in the second shell number nine

Florine nine protons and nine electrons electron configuration 27 two electrons in the first shell and

seven in the second shell number 10 neon 10 protons and 10 electrons

electron configuration 28 two electrons in the first shell and eight in the second

shell remember how many electrons that the second shell can take before it's full

eight this means that neon's second shell is full this has important consequences for

neon and makes it an unreactive noble gas we will explain why this happens later can you guess what might happen if

we had another proton and electron where would the electron go and what element is

this we've just built atoms of the first 10 elements on the periodic table each one has a different number of

protons and electrons and a different electron configuration too as you learn more about atoms you

will discover that these elements are what they are because of these protons and electrons and how they were put

together for example hydrogen is an explosive gas because it has just one electron in its outer shell and

helium is an unex of gas because it has two electrons in its outer shell and lithium is a shiny metal

because it has an electron configuration of 21 we will explain how this works

later our world is as it is because of these little subatomic particles and how they are

arranged that is because of atomic structure [Music]

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