Covalent Bonding! (Definition and Examples) - YouTube

In this video I'll be going over the definition of covalent bonding how to

identify a covalent bond and then I'm gonna just get into how to start drawing

out covalent bonds so the overall definition is the type of bonding that

happens between two or more nonmetals so no metals allowed in covalent bonds

in order to identify whether or not something's a metal or a nonmetal

we're going to have to use the periodic table and so no matter how your periodic

table is organized and all of them look a little bit different in terms of

colors and groups overall it's broken up into two parts the metals and the

nonmetals and so you want to follow this staircase and so with the exception of

hydrogen which we'll get to in a second everything to the left of this staircase

is a metal and everything to the right is a nonmetal and the only exception is

hydrogen so the metals are everything inside of this black line and the

nonmetals are everything outside of it all right so next in covalent bonds

electrons are shared not transferred and a lot of the points I'm going to go over

are basically there to contrast against ionic bonding which is probably the

other type of bonding you're going over now in your class and so with covalent

bonding it's all about sharing it's not about giving up or receiving electrons

and so next atoms will be neutral or have partial charges sometimes but never

any full charges again contrasted with ionic bonding so when you're drawing out

covalent molecules you don't have to worry about putting a plus one or minus

one or any let's stuff like that on top of them it's pretty much they're going

to be neutral and then once in a while you'll do a practice problem where

teacher is going to ask you to show a partial charge but that's not on most of

them and so next the bonds are drawn as sticks when you're connecting to

different atoms that happen to be in a covalent bond you just connect it with a

simple line like this and then last in our definition bonds represent the two

electrons that are shared between the nuclei so in covalent bonds that stick

that bond it really means something it's not just there to show a connection

although it also does that this stick literally equals two electrons alright

so next let's go over a few examples of molecules and identify if they're

covalent or not so first we have CL 2 and so this just means that we have two

chlorines chlorine is right here number 17 it's definitely in the nonmetal

category so this means that we have one nonmetal that's chlorine and then

another nonmetal or second chlorine so this molecule is covalent so next na BR

we have sodium up here at number eleven and we have bromine over here at number

35 so we have one of our atoms is in the metal category this sodium is a metal

even though bromine is not so this means that this is not covalent a metal and

nonmetal that's going to be an ionic bond all right so next al to s3 we have

al right here and we have s right here and so aluminum even though it's just

two left without line it is to the left of it so it means that this is a metal

and sulfur that's to the right that's a nonmetal so once again metal and

nonmetal that's not the definition of just two or more nonmetals so this means

that this is not a covalent bond and so last we have h2o

so H right here that's our exception that is a nonmetal and we also have

oxygen over here another nonmetal and so this is also a covalent bond all right

now let's go ahead and start drawing these out and get a little bit more into

what's exactly happening in that covalent bond all right so let's take

our example from before of cl2 and knowing that our subscript is just

telling us how many of that element we have and we have a two here we know this

is the bond between two chlorines and now I'm going to go ahead and draw in

chlorines valence electrons and so if that sounds confusing to you or you need

a refresher go ahead and watch my video on valence electrons and then come back

to this spot but for right now we know that chlorine is in the seventh column

when we skip the transition metals in our periodic table and

means that it's going to have seven valence electrons and because of our

octet rule we know that every atom wants to have a full valence shell and so for

chlorines it already has seven that really means getting one more it means

getting eight and so ideally chlorines life would go something like this

it would be in a situation where it met an element that really wanted to give up

an electron so for instance sodium really wants to get rid of its one

valence electron so if these two met sodium would just go ahead and it would

just give its electron to chlorine and then it wouldn't have any valence

electrons and chlorine would have its full eight and then both of these would

be happy but over here on the left hand side our actual example we don't have

any sodium's in this situation let's say what if it's just a pile of different

chlorine atoms well what's gonna happen is that these chlorines are gonna kind

of make a deal with each other they're gonna say okay we're not in a

situation where either of us can get what we want because both of us just

want someone to give us an electron so instead they're gonna make a little

bargain and the bargain is gonna be well why don't you give me an electron for

part of the time and then for part of the time

I'll give you an electron and so this is a really a weird analogy that's kind of

silly but I think it does kind of work just roll with me think of these two

atoms as two friends that want to buy a really expensive pair of shoes all right

so let's say these two friends really want this pair of shoes it's $1,000 but

neither of them can afford it they just each have $500 and so you can kind of

see what's gonna happen right if their best friends are gonna say oh okay well

how about this we can both just put our money together and then we can buy the

pair of shoes but then after we have the shoes we don't want to split them up

right that does them no good you want your pair of shoes so instead the

friends are gonna create a schedule and they're gonna say something like okay

you take the shoes this weekend I'll pick them up next week or you have them

for January I'll have them for February etc and we'll move the shoes back and

forth between us all right so this again is silly but it really is

what these two chlorines are going to do so what's going to happen is that

they're gonna say okay fine some of the time you're gonna be able to just take

my electron electron so let's say this chlorine on the right says okay some of

the times you can have all your seven electrons plus you can visit mine so

then this chlorine on the left looks like this and the chlorine on the right

looks like this but because this corn on the right agrees to give up its electron

it's gonna say okay pretty soon you're gonna have to just give me two electrons

both the one that you took from me and one of your own and so if we go all the

way up top this kind of looks like this this chlorine says okay some of the

times I'm gonna take yours and I'm gonna take my original one back and so if this

was just you and a friend with shoes you would make some schedule that makes

sense for you guys so these two chlorine atoms are going to make a schedule of

sharing back and forth that works for them and so what that means is something

super fast electrons generally move at about 2,200 kilometers per second that's

enough to go around the earth in 18 seconds so these two electrons are being

shared in this covalent bond back and forth between the two chlorines millions

billions trillions of times every second and so because this transfer of back and

forth is so fast so fast so fast in the essence it just sticks the two chlorines

together so the two chlorines don't really care about being together they

just care about having their electrons and because electrons are moving so fast

back and forth there's never any time for the chlorines to break apart they're

now essentially just stuck together and that's what a covalent bond is so when I

draw it out now I just draw the stick the line as the two electrons moving

back and forth super fast in between the two chlorines and then we each have six

valence electrons that are not participating in any bonding so you can

see up to my image up here these six electrons that are not involved at the

beginning in any of the sharing are not at the end they're just here by

themselves and the two electrons got caught in the middle of the shearing

they become the bond so we don't show them anymore so every time you're

drawing a covalent bond you want to make sure you understand that that bond

actually equals two electrons and you don't want to show those electrons

anywhere else in your picture so just to kind of finish up with the shoe analogy

basically these chlorines are stuck together it's the same thing as if when

you and your friend decided to get this expensive pair of shoes you said we're

gonna switch back and forth the shoes every three seconds for the rest of our

lives well if that was true you would never separate from your friend again

you would always have to go to the same place because to switch back and forth

every three seconds you'd have to switch back and forth your shoes and you'd have

to just be physically close to that person and so again the electrons are

moving way faster than that but it's an example of why sharing something back

and forth so fast can make you be stuck next to something else that's what's

happening these chlorines are stuck next to each other all right so now let's do

one more example and that's the other covalent molecule that we had and that

was h2o so again starting by just drawing out valence we have two

hydrogen's that's our subscript of 2 so H with one H with one and O has six

valence again can't emphasize enough this doesn't make sense to you go back

and watch another video on valence electrons and don't try to do this

unless you totally understand valence electrons already all right and so now

we have one valence one valence and we have six valence and so everyone wants

to have a full valence shell for this that means that H wants to get up to 2

and oxygen wants to get 8 and so the way the sharing is going to happen is first

we're not going to connect the two H's to each other if we did that there'd be

nowhere for oxygen to connect because the two H's would just have each of

their own electron so we're going to connect each H to the oxygen atom so

what's going to happen is again just think of it as that shoe analogy this H

on the left and this oxygen or say okay some of the time I'm gonna give

you my electron and in exchange the other half of the time you're gonna give

me your electron plus the one you borrowed from me so for this H will be

like this it doesn't matter what electron it is just as long as it's on

the oxygen and then the other hydrogen says the same thing says I'm going to

take one of your electrons for half the time and in exchange I'll give you mine

half the time and then the oxygen says okay that's great then what I'm going to

do is I'm going to half the time take back not only this electron but also

this electron and that's how I'm going to get my eight so let's draw this

another way so oxygen we can see has four electrons on the top but didn't do

any bonding and now it made a bond to H and another bond to H so now that you've

seen this happen let's do another picture that tells you how to make

covalent bonds a little bit faster so back to our valence electrons because

remember a really important thing is that we don't want to have any electrons

that are involved in bonding show up in our final structure so what I like to do

sometimes is just do the connect-the-dot way so we just say okay this hydrogen

electron and let's just connect it to another random oxygen electron we're

gonna connect those dots those the two electrons are going to form in a bond we

do the same thing over here and now that we have that I'm going to redraw so our

picture looks nice and tidy so oxygen and we had in this one four electrons

that were involved in no bonding we made two bonds and they were each connected

to a hydrogen so what we've done is basically an intro to Lewis structures

Lewis structures are all covalently bonded and they basically tell you how

to draw out more complex molecules so you know if we had something like this

it would be hard to look at all of these one carbon two hydrogen's two chlorines

and immediately know how to connect so once we get into more advanced covalent

structures you need to look up Lewis so that you can learn the rules of how

you would connect these atoms all right that's my intro to covalent bonding and

happy studying hey I hope you liked that video please

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happy studying