- In this video, we're gonna obtain even an ext appreciation for why the periodic tableof elements is therefore useful. And also in particular, we're walk to focus on groups of the regular table the elements. Once we talk around a group, we're simply talking around a column. And also as we'll see, also thoughthe aspects in a offered column might have really different atomic numbers, they all have similar properties. And also the reason why castle allhave comparable properties is, in many cases, they have the same variety of valence electrons. Remember, valence electronsare the reactive electrons, the ones the mightinteract with other things. And because elements withsimilar valence electrons will have similar reactivities,they will type similar ions. Comparable ions. And they will have comparable roles. Comparable roles in ionic compounds. Ionic compounds. Now, for the services of thisvideo, I'm gonna focus most on the extremes the the regular table, the teams at the left and the right, due to the fact that those are the closestto having actually a complete outer shell, either by losing electronsor by obtaining electrons. So just to repeat ourselves, what walk it median to havea full, complete outer shell? Well, in general, peoplewill describe the octet rule. Because that our second, third, fourth,fifth, and also on and also on shells, you're complete when you have actually eight electrons. Eight electrons. The major exception to theoctet dominance is the first shell, where it is full with 2 electrons. So helium, even though itonly has actually two electrons, is very, very, an extremely stable. And also the major data suggest thatwe have about this octet preeminence are the group 18 elements right over here, also known together the noble gasses. They're known as the noble gasses due to the fact that they're very unreactive,they're very content, castle don't wanna messaround with anyone else. And also that's because all of the noble gasses have complete outer shells. Helium's external shell is thefirst shell and it's full. Neon's external shell's thesecond shell, it's full. Argon's outer shell is thethird shell and it's full, and also so on and so forth. Now, if we go one team tothe left of the noble gasses, we acquire to the halogens. Now, the halogens haveseven valence electrons. So you deserve to imagine, they'reonly one electron far from having actually an electronconfiguration prefer the noble gas come the best of each of them. So this halogens right over here, these really favor to attract electrons to form a an adverse ion or an anion. So you'll oftentimes seefluorine together a fluoride anion, for this reason it has a an adverse one charge. Or you'll also see chlorinewith a negative one fee as the chloride anion. And also I might go on and also on. You'll often see iodine obtain an electron and have a an adverse one charge. If you go one step to theleft, the oxygen group, oxygen, sulfur, and also on and also on, these facets have six valence electrons. Therefore it's still much easier for themto have actually a complete outer covering by gaining two electronsthan by shedding six electrons. For this reason these facets alsolike to tempt electrons. So you deserve to see oxygen together an oxide anion. That has obtained two electrons, it's swiped that from somebody else. Sulfur together a sulfide anion. Now, if you go to the otherextreme of the regular table, if friend look at team one elements, they have one valence electron. And also especially the ones the you look, and you see in red here, i beg your pardon are well-known as the alkali metals, it's much easier forthem to shed an electron to have a full outer covering than because that them to gain seven electrons. The reason why hydrogen'sa bit of an exemption is that doesn't have actually to get seven electron to have actually a full outershell, it has to obtain one. So hydrogen might lose one, and also essentially have actually no electrons, or it can gain one electron and also it would have a fullouter shell choose helium. However when we think about ionic compounds, these alkali metals are really some of the most amazing participants. Since as you have the right to imagine,for them to acquire stable, they wanna give away an electron. So you're really likely to check out them having provided away one electron and also having a positive one charge. So you'll oftentimes see a lithium ion with a confident one charge, a salt ion v a optimistic one charge, a potassium ion witha positive one charge. And that's, in general, true of all of these group one elements. Now, what around these group two elements, also known as the alkaline planet metals? Well, as soon as again, it's easierfor them to shed two electrons than for them to obtain sixand have a full outer shell. So, you'll frequently see beryllium having actually a confident two charge. It would have actually lost those two electrons. Magnesium as having actually a optimistic two charge. Calcium as having actually a positive two charge. Now, given that, just how wouldyou suppose things on the left and things on the rightto type ionic compounds? for this reason you could guess, ifyou have an alkali metal in the visibility of a halogen, things could get really reactive. In fact, points will get really reactive due to the fact that these wanna offer away electron, these wanna take it electron. And also that's what will certainly happen. The electrons will certainly leavethe team one elements and then they will go to the halogen. And also in the procedure it mightrelease a most energy, however what you'd be leftwith is one ionic compound. Because that example, lithium loses a electron and also has a positive one charge. That optimistic ion wouldbe really attracted to a chlorine anion that hasjust gained an electron. Maybe it's the very same electron, or the swiped the electronfrom an additional lithium atom. And also so these two points would it is in attracted and they could form lithium chloride. And every one of these alkali metalscould play that same duty in this ionic compound as lithium. So it's additionally typicalto view sodium chloride. The is table salt. It's likewise typical tosee potassium chloride. So on and so forth. And on the various other hand,fluorine or bromine or iodine can play a similar duty as chlorine. For this reason you can see somethinglike salt iodide or potassium iodide. As soon as again, the alkali metalwould have lost one electron, the halogen would certainly have gained an electron, and then they're attractive to each other in creating these ionic compounds. What kind of ioniccompounds can be created with these group two elements? Let's take calcium, for example. It's no unreasonable forcalcium to shed two electrons to have a stable external shell, to have an electronconfiguration favor argon. Therefore if the loses two electronsit has a optimistic two charge. And also you can imagine,those 2 electrons get lost to two various iodine atoms. So every of them have a negativeone charge, so times two, and also then what kind of ioniccompound could they form? Well, you might have onecalcium and then 2 iodines. So calcium iodide is actually an ionic compound you would see. It has a neutral charge overall because calcium has a positive two charge and also each that the iodineshave a an adverse one charge, yet then you have actually two of them,so it is neutral overall. What could calcium do with oxygen? Well, calcium likes to shed two electrons, oxygen likes to acquire two electrons, therefore you can see somethinglike calcium oxide. Therefore I will certainly leave friend there.

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The big picture below is, thecolumn in i beg your pardon an aspect is tells you a lot about its reactivity since it tells you in general how many valence electron it has. And also atoms are most stable whenthey have actually a full outer shell and so that helps girlfriend predict,hey, is it simpler for them to shed electrons and kind a positive ion or obtain electrons and type a negative ion? and then native that, youcould do predictions as to the types of ionic compounds that could be developed withthe various elements.