Electronegativity

Hello everyone, my name is Chris Harris and I'm from al.com and in this video we'll look at

electronegativity

. Electronegativity is a very important foundation, concept to get right, mainly because you need to know. It's to understand things like organic mechanisms, uh, in A2 chemistry and beyond, so it's very important that you need to know this and also, especially for chemistry, when you need to know the definition and you need to know. Pretty much what the numbers mean in terms of that, so let's start with the definition of electrical negativity and you can see here that the definition is the ability or power of an atom to attract electrons to itself in a coent bond. uh and the two most crucial parts of this are the ability of an atom to attract electrons, which is the first bit um and uh the hot bonding bit is also important and you get electro negativity in molecules bonded with co um and when Yes you have

electronegativity

, you can also have a little bit of ionic character and remember that ionic character is when you actually take an electron from one atom and donate it to another to create charges, and this is kind of half the battle, except that You don't create proper full charges, but you do create small charges, and that's what makes these molecules also have some ionic character, and most molecules in chemistry actually also have a little bit of ionic and concentrated character, but some molecules, for example, H2. and cl2, so those where you have two atoms that are the same actually have a purely cogent character and not an ionic character mainly because there is no polarity there, so there is something called the Poing scale and Poing was a scientist who basically came up with numbers to say how powerful each atom was at attracting electrons to itself when it was bonded to another atom, so he came up with this series of elements here and you can see we have hydrogen at the top and we go down to Florine at the bottom and Florine has the largest number um and this means that Florine is actually the most electronegative element, which means that it actually attracts electrons more strongly to itself.

If you have to visualize this on a periodic table, you will find that it is actually further to the right. and up the periodic table you go um the more electronegative the element is um if you exclude group eight or group zero whatever you want to call it, in this case the highest and to the right is Florine and Florine is the most electro negative class and how much The further you get away from Fling, whether to the left or down, the less electro negative your element becomes, so we'll look at this here and see what effect this electro negativity actually has because it plays a huge role in terms of how the reactions, so let's start with HCL.

Now you can see here that H has an electronegativity of 2.1 and what that means is that it is not as electronegative compared to chlorine, which has a negative electron. electronegativity value of three um, which means that chlorine will actually attract electrons to itself more than hydrogen and what that means is that you get like a polarity, you get a charge difference and we can represent this using these symbols here, which is Delta positive and Delta negative, so because chlorine is more electronegative than hydrogen, it attracts electrons to itself and forms what we call a negative Delta charge and obviously the hydrogen would form a positive Delta charge because now they are being removing the electrons.

What does this mean? is actually in their electrons in this bond, here they are actually the ones that are shared between them, they are actually being attracted slightly towards the chlorine side than towards the hydrogen side and this polarity can actually lead to more reactions and you will encounter this. so many times through our chemistry ace and A2 uh and you'll see when you do mechanisms and other reactions you'll see where this fits now if we do a different one so if we do HF which is hydrogen fluoride um again Florine is very electronegative um he's very willing to accept the electrons or take the electrons when they are shared um so again the polarity is there and Florine would have this negative charge Delta and the hydrogen has the positive Delta and what you have What I have is that the electrons are pushed more to the side flourishing.

Now you need to be able to write this polarity here as well and this is really important when you do intermolecular forces, when you do dipole dipole and Vander interaction. okay too and even hyden bonds so all three of them really use this idea of ​​electro negativity and if you want to watch that video just click on the link right below and you can see how electro negativity and polarity affect uh like intermolecular . force now there are some exceptions where it gets a little bit different so here are the exceptions so you might have something like carbon dioxide where you can see the carbon has the positive Delta and your oxygen is negative Delta because They are more Electro. negative compared to carbon, uh, because it's actually a symmetrical molecule and these two negatives will actually cancel each other out and generally this molecule at first glance might look polar, it's actually not, because of this, this symmetry here and the two. the negatives will cancel each other out so this is actually non-polar and it's the same with this one here which is nf3 um again you have very electronegative lines there um but you have a lone pair on that nitrogen and that lone pair can actually balance each other out.

It takes out the negative charge at the bottom and actually balances it at the top as well, because the actual electrons are evenly distributed throughout this molecule. nf3 is actually not very polar and you can tell if something is polar. For example, one of the key examples is water, and water obviously has oxygen, it has two lone pairs on oxygen, you have a positive hydrogen delta and a negative oxygen delta, because oxygen is more electronegative than hydrogen, it is More to the right. on the periodic table and actually, um, if you turn on a faucet very, very, very gently, um and like a trickle of water coming out of the faucet, uh, and if you take like an acetate rod and rub it to give it a charge , if you put that rod close to the stream of water, then what you should find is that actually the water should start like a star and bend around that rod, because if your rod is charged and your water is actually charged, it has a polarity, then the water is actually charged. affected by any charged object that is placed near it, so you can try it, if you have a feather duster and some plastic, especially pect, which would be very good for that, then, this is electronegativity and you need to know the little symbols like Positive Delta and Negative Delta, the definition is crucial, uh, and if you understand this concept, then it will help you tremendously for further ideas in chemistry and also, and if you want to pursue a degree in chemistry, then that would be help as well but that's all bye.