Predict Atom Charge: Bohr Model, Valence Electrons & Noble Gases

hello everyone and welcome back my name is mr covald and in this video i'm going to show you how to predict the charge of

an atom understanding what's going on at the atomic level with the electrons

so let's get into this but before i begin please make sure you uh

subscribe to my channel like this video if you uh if you like it share this video make

comments in the comment section subscribe to my channel hit that notification bell

okay let's get into this okay so um how do we predict the uh charge of an

atom okay so i'm going to be using the bohr model the board model is not the most

accurate model but it is a simplified version that allows us to explain things easily um so giving that in mind that

this is not the correct model but this is enough to help explain what's going on here so

when we're looking at the bohr model of each of these atoms you can see that there are rings and that each of the

rings has a certain amount of electrons in them and so there is structure to this atom and so one of the things that

you want to keep in mind is that all atoms react

in order to be like noble gases what is a noble gas that is the those are the atoms in the last

uh the last column of your periodic table all the way to the right usually there's an aid above it

so that's uh ro sorry

column eight we call those columns families or

we call them groups we'll get into that later in a later video i don't want to get too much in the periodic table i'll

talk about the periodic table and how it relates to charge in just uh in another video but with the

important thing is is to see that each atom has a certain number of electrons in it

we learned that the number of electrons if we're assuming a neutral atom the number of electrons are is equal to the

number of protons so if you have eight protons in your nucleus to balance that charge you need

eight negative electrons so in lithium lithium is number three on

the periodic table so therefore its atomic its atomic number is three and therefore the number of protons is three

and you can see that i have three electrons written in my atom here so you can see that in here

according to the bohr model i have two rings around my nucleus the nucleus is at the center

and so the first ring has two electrons orbiting the nucleus

and here we have one electron orbiting on the outer shell here or the outer ring

here and so we're

kind of figuring out okay so what's going on at this level so the key to understanding

what's going on when electrons become ions in order to do that um we have to understand why they lose

or gain electrons so remember elec atoms are going to become ions by either losing or gaining electrons

if they lose electrons they're going to be positive because they're they don't have enough electrons to balance out the

charge of the protons so that makes them positive if they gain electrons that's going to make them negative because the

electrons are negative you've got more electrons than you do positive protons and so you've got a negative charge and

that's all going to depend what what charge they have is going to depend on the number of electrons they lose or

gain but the question then comes up

what determines how many electrons they lose or gain and that there is related to the noble gases the noble gases is

key to understanding this so the noble gases that group all the way to the right of your periodic table that

number eight group that eight is a magic number it's a very important number keep that in mind we'll talk about that uh in

another video but i'll hit on it here a little bit so you'll notice here

that i have two noble gases so helium is in the first row

and uh neon is in that second row we call those rows periods again we'll get that to that in another video

so helium is uh at the top of the eighth group

all the way to the right of the noble gases it's the first one on top and then the next one is neon on the bottom

and so you'll notice that the shell here for helium has two electrons

and you'll notice here that the inner shell here of lithium

beryllium boron and nitrogen all have two electrons in that first shell

just like helium right and the same thing i got oxygen and

fluorine here so they also have they have two and two in that first shell

and you'll notice that i've written out the atoms in that second row that second period so

that second row or period of the periodic table is lithium beryllium boron

nitrogen oxygen fluorine i skipped carbon for a reason i'll get to that in a moment so

let me just show you the periodic table what i'm talking about here

so you'll notice i have here this is this is your group 8 over here

so you'll notice it says group 8 or 18 or 8a so there's two ways numbering this so 8a

is what i'm looking at here so you'll see helium as the first one and you'll see

neon as the second one and if you go across the row here right so here you have lithium oops

you have lithium there you have beryllium and then on the other side you have

boron carbon i skipped and then you have nitrogen

[Music] oxygen fluorine and then neon so that's there on your periodic table

so here's what the structure of the atoms look like

so you'll notice again that the inner shell has two electrons and that is just like helium so after

helium on the periodic table all the atoms have two electrons so that seems to indicate

that that first shell only can hold two electrons maximum okay so that shell is considered full

okay here neon

that second shells has two electrons but then you'll notice that neon has eight electrons

so that shell would be considered full as well so any atom after neon is going to have that full shelling

and notice when i go from helium to lithium i add a shell

right so you can imagine if i go from neon to the next one

which i believe is uh calcium let me look sodium my bad sodium

so sodium would be next after neon and so you add electron

where is it going to go if this is full where is that electron going to go it would go to another cell so you would

have to add another third cell to it so you add a third cell around here that electron will go in that shell and so on

so that's the first thing i want to kind of point out this kind of pattern here okay

so hopefully you understand what i'm pointing out why is this important why am i pointing out oh this this first

shell is full with two electrons and this second shell is full with eight electrons

eight electrons however that works on my hand i'm holding a marker so it's hard to show so it's full with eight

electrons okay so why is that important so the noble gases

have a full outer shell they are stable because of that so

noble gases aren't going to react right noble gases aren't going to react why

because they have a full shell so all of uh all of chemistry all of these reactions

are in large part due to the fact that atoms want to have that full shell just like noble gases so all the elements all

the atoms want to be like noble gases just like all basket players want to be like mike

sorry i'm from chicago so that's the way it is so michael jordan is the goat okay so

moving on so why so when we're trying to understand why these atoms

lose or gain electrons um we have to think well they want to be like a noble gas

so they're either going to lose electrons or they're going to gain electrons to be like a noble gas

and so we have to look at which noble gas is closest to your element so i have these

written down here so if you look at lithium which noble gas on the periodic table

is closer to lithium take a look right now

i'm serious take a look right now which one is closer yes

so lithium lithium is closest to helium right

helium is closer to lithium and so you can ask yourself okay so lithium has one electron on its

outermost shell and by the way we call this outermost shell the valence shell and electrons on that

shell are called valence electrons so if i ever use the word valence electrons you

know what i'm talking about valence electrons are the electrons on the outermost shell which is called the

valence shell so we have one electron on the valence

shell one valence electron so it could either lose that one electron

to be like helium or it could gain seven electrons

to be like neon so the question is which is easier to lose one electron or to gain seven

obviously it's easier to lose one so that's exactly what it's going to do so that lithium atom loses one electron

now of course that one electron doesn't just go out into space actually it needs something else to take that electron

away right so we're not going to get into that that gets into ionic bonding and

and all that stuff or covalent bonding with that will come later but right now the important thing to notice is that

lithium is going to lose an electron to another atom and then it's going to

have two electrons here and no electrons here in this

outer orbit so really that the outer orbit is empty so that outer orbit is no longer the outer outermost shell or

outermost orbit is now this one is the outermost orbit now it has a full outer shell

so now it's just like helium which is a noble gas

but it lost an electron so now it has to have a charge so it lost a negative

electron that means there's one proton not being balanced so that's a positive charge so that means

lithium has a plus one charge we don't write the ones we just write a plus so it's got

plus one charge there does that make sense okay hopefully it does let's go to the

next one so brilliant brilliant has two electrons on its outer outermost cell so that's

two valence electrons and so again the question is what is this element going to do what

does this atom want to do it wants to be like a noble gas so

which noble gas is it closest to right so

it could either lose these two electrons to be like helium or it could gain six electrons

to be like neon if you look on the periodic table you'll notice that helium is closer

because and it also makes sense that losing two electrons is easier than gaining six

so it's going to lose those two electrons to some other atom right so in the

process in a chemical reaction with beryllium beryllium is going to lose those two

electrons so it loses two electrons to some other atom or atoms and so in the process it loses

those two electrons the outermost electrons are the ones that are lost not the

not those it's the outermost electrons those are the easiest to remove the reason that

those are easy to remove is because the energy of the electron gets larger or the farther it gets away from

the nucleus those are easier to remove and so we'll talk

about more i don't want to get into the weeds of that um but just note that the outer most

electrons are the ones that get removed not the innermost so the outer ones okay so then that means

that this atom now of beryllium no longer has two electrons

in its outer shell right so it has two electrons let me go back

to lithium i'll write here make this more obvious this has three protons plus positive protons and so you

have two electrons negative electrons you have three protons and so there's

a positive one charge so that makes that more uh more obvious here we have two

electrons but beryllium has an atomic number of four that means it has four protons

so we'll have four p plus but it only has two electrons because it lost two electrons

to be stable like helium a noble gas and so now the charge on that has to be a two plus charge oops wrong simple

a two plus charge okay so far so good oh flights

sorry about that so what about boron borane has three

electrons and so keeping the pattern so we look at

the noble gases it wants to be like a noble gas so either it's going to lose three

electrons to be like helium or it's going to gain five electrons to be like neon which is easier to do

obviously heal it and helium is closer to it on the periodic table so in order to be like helium it's going to

lose those three electrons so again those three electrons are going to go to some other atom in the reaction

and then again we end up with only two electrons on this inner shell

and so this orbit goes away so the outermost orbit is the two electrons here

so it now has a full shell again this has a full shell outer shell and so these are now stable

like helium and again boron has five protons in its nucleus it now has only two

electrons so that's only going to balance out two protons so there's a three protons that are not balanced so

that means as a positive 3 charge so we write that as b 3 plus

and we can keep going like this now i'm going to jump over carbon and we're going to go to nitrogen so you'll see

nitrogen here nitrogen has two inner electrons but the outermost shell the valence shell has

five electrons so it has five valence electrons so what is this going to do

so again it could either be like helium with two electrons or it could be like neon with

eight electrons so which is easier is boron gonna lose those five electrons or is it gonna gain three

yes you're correct the answer is it's gonna gain three electrons so instead it's gonna gain three oops

three electrons now again those three electrons just don't come out of thin air they're gonna

come from another atom that it's reacting with but the point is is that it's gonna gain through those three

electrons so it can be stable like a noble gas it wants that outer shell full and for the second shell here

that number is eight just like neon so

the atom has two electrons in the outer shell and

it's going to have eight electrons in i'm sorry the inner cell has two electrons and the outer shell has eight

electrons so that's four five six seven eight and so now this

is complete it's now stable but it gained three electrons so

the charge on nitrogen is going to be a three minus charge because how many

protons does this have nitrogen has

seven protons and here you have a total of 10

electrons so you have three more electrons than you do protons that's a negative charge so that's a three minus

charge okay let's go on to oxygen and fluorine same thing

oxygen has six valence electrons in its outermost shell and so therefore the question is is it

going to lose those six electrons to be like helium or is it going to gain those

uh two electrons to be like neon and again it's easier to lose it's easier to gain those two electrons than

to lose six so it'll gain those two electrons from somewhere right so it's going to gain

them from some atom somewhere and so you get those two electrons coming in and you now have an outer

shell one two three four five six seven eight and there's two on the inner shell here

and so gaining those two electrons we know that uh because this is

on the periodic table you we know that it has oops eight

protons because its atomic number is eight and it has 10 electrons so two electrons

are not balanced out so we have two negative charges that are not balanced by the positive protons and so that

means that oxygen has a two negative charge on it and finally for fluorine fluorine

has seven valence electrons and

that means that can either gain one electron to be like neon or it can lose o7

obviously it's going to be easier just gain that one electron from somewhere and so that means

that it's going to have an extra negative on there

one two two electrons in the inner shell one two three

four five six seven eight electrons in its outer shell so again a total of

10 electrons the number of protons here is nine so it has nine

protons and so that means it has one extra electron so

the charge on fluorine is going to be a negative one again we don't write the ones

and so here again the upshot of all this is that atoms are going to lose or gain electrons in order to be like the noble

gas whichever noble gas is closest that's the noble gas is going to be like and you can understand that from the

fact that which is easier um if you have uh less than four electrons it's going to be easier to

lose those electrons to gain you know six seven or eight electrons or five four electrons

and so on so this is how you can understand whether or not an atom is going to lose

or gain electrons and get that charge right so if it's going to lose electrons if it's closer to one element and it can

lose less electrons and gain those electrons it's going to lose those electrons

and so losing electrons gives it a positive charge and if you are if you have

five or more electrons in your in your outer shell then it's going to be easier just to gain more electrons

than to lose those electrons to be like the next noble gas then it's going to do that and it's

going to have a negative charge okay so why why do i skip carbon though what about

carbon well carbon is number four smack dab in the middle right so if you have

no if you have number eight right so let me use my periodic table again let me show you the periodic table

so you'll notice over over here we have group one so up here we have group number one

so group number one here we have lithium right that's group number one and then here beryllium that's group

number two and then over here you have group number three

four five six seven and then eight everyone wants to be like the noble gas so

guess guess which group is in the middle so we have nitrogen which is five oxygen is in group six

fluorine is group seven so there's three on this side and then you have lithium beryllium and then over here boron three

on that side and then you'll see carbon is right in the middle that group 4. so since they're in the middle

they can either lose 4 electrons to be like the previous noble gas

helium or they can gain four electrons to be like the next

noble gas neon so because there's in the middle it's a little more difficult to predict

what charge those elements will have so i skipped carbon because it's kind of an odd ball

but the rest of them uh if you understand what's going on here and you understand like how many valence

electrons they have they're going to lose or gain electrons to be like a noble gas to fill

that outer shell and so i hope that explains everything i hope that's clear to you

if you have any questions please put them in the comment section if you like this video please

hit that like button smash that like button and uh hit that notification notification bell subscribe to my

channel so that you can be notified by any other videos i put out thanks for joining me and have a great

day