Learn about Junior Chemistry, Compounds 1, in this comprehensive video by bannanaiscool.
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Male Speaker: Little bit of a candle light, I will see you through, may be a little more intense in candle light heat up a piece of magnesium, here we go, Mg plus O2, MgO is being produced and that's quite a good amount of light, candled directly out there of course you can on DVD, I can what I'm looking at it but interestingly look at that. There is no more magnesium there, that's a compound magnesium oxide. So magnesium and oxygen may come together and make magnesium oxide but why those elements want to do that in the first place. Well, elements like to be able to bond together to lower the total amount of energy they have as individuals when they come together they release energy and form the new system that is actually more stable than the two of them were apart, that's the whole idea behind the whole universe, its stability gained through this type of chemical bonding. Now electrons are actually shared in chemical bonds or they are actually transferred or exchanged. Let's talk about the ones now where electrons are transferred. Generally it's between a metal and a non-metal or a cation and an anion. So Na positive here is the cation and F negative the anion. Now, why do they have those particular charges, you can look it up on the periodic table it has to do with their tendency to be able to gain or lose an electron or electrons it might be more convenient for them to lose two or three electrons to become more stable. In the case of sodium, it likes to be able to lose one electron if you can use that word like, sometimes it will be personified in chemistry are and prop modifies things and kind of reduce it down to the human level but of course elements don't want, they don't desire they don't like anything but what sodium has a tendency to do is to lose one electron when given enough, just a little bit of energy in order to do so. Now fluorine on the other hand, don't likes to acquire likes to see acquire an electron to be able to become more stable and so if Na is a positive and F is a negative charge, you can look those up on a periodic table, then when these two actually do that type of exchange an electrostatic interaction keeps them together because one is positive, one is negative and dislike charges will attract one another. So how many Nas does it take to bond with F in order to get a stable compound. I lose one electron, I will gain one electron and so the formula is NaF, that's the formula for that compound sodium and then we take fluorine and then we say okay drop the ine and add ide sodium fluoride. Now, you take a look at magnesium which actually can lose two electrons that's on periodic table check it out, chlorine wants to gain only one so what's the story there. Magnesium as said again going to lose two electrons, this is but they only require one, so if that's the case then you need another chlorine to combine another Cl negative and both of these can each gain one for a total of two so this is where we get the formula for magnesium chloride, one magnesium for every two chlorines and the name of that compound magnesium chloride. Now you can say well you know what I just learned that you can just take that two and put it down and take that one which is there and put it down and you get formula. Well yeah okay that's a kind of a convenient way to do that but I hope you understand you got to understand and you have to understand that this is the principle that we are going by here. There is no real exchange of charges; there is just only two of these for every one of these. Now hope that you get that. Now look at this one for instance. You got tin with the two positive and O with the two negative. See and a lot of chemistry students who are actually quite bad would say oh just put the two there and the put the two there and there we got it. No, no, no you can't do that, you can't do that. You have to understand that this will say I want to lose two elections and I want to gain two electrons so the ratio of r