- so let's talka small bit about groups that the routine table. Now, a very an easy wayto think about groups is the they simply are thecolumns of the routine table, and also standard convention is to number them. This is the an initial column,so that's group one, 2nd column, third group,fourth, fifth, sixth, seventh, eighth, groupnine, group 10, 11, 12, 13, 14, 15, 16, 17, and also 18. And I know some ofy'all can be thinking, what around these f-blockelements end here? If we were to properlydo the routine table, we would shift all of these, everything from the d-blockand p-block rightwards, and also make room for these f-block elements, yet the convention is isthat us don't number them. But what's interesting, whydo we go through the trouble around calling one of these columns, of calling these columns a group? Well, this is what's interestingabout the regular table, is that all of the aspects in a column, because that the most part, andthere's lots of exceptions, however for the most part,the aspects in the shaft have an extremely very very comparable properties, and that's because theelements in a column, or the facets in a group, have tendency to have actually the same variety of electrons in their outermost shell. They tend to have actually the samenumber the valence electrons, and also valence electrons andelectrons in the outermost shell, they often tend to coincide, although, there's a slightly various variation. The valence electrons,these room the electron that are going to react, which have tendency to be theoutermost shell electrons, yet there are exceptions to that, and also there's actually a lotof interesting exceptions that occur in the transitionmetals, in the D block, however we're no gonna enter those details. Let's simply think a small bit about some the the teams thatyou will hear about, and why they react in very comparable ways. For this reason if us go with group one, team one, and hydrogen is a tiny bit of a strange character, since hydrogen isn't do the efforts to obtain to eight valence electrons, hydrogen in that very first shell simply wants to gain to 2 valenceelectrons, choose helium has, and so hydrogen is sort of, it's not, that doesn'tshare as lot in usual with whatever else in team one together you can expect for, say, all of the points in team two. Group one, if you placed hydrogen aside, these room referred toas the alkali metals, and also hydrogen is notconsidered an alkali metal, for this reason these best over here are the alkali, alkali metals. Now why do every one of thesehave very similar reactions? Why do they have very similar properties? Well, to think around that, you just need to think abouttheir electron configurations. So, because that example, the electronconfiguration because that lithium is walk to be the same as the electron configuration of helium, of helium, and also then, you're going to go toyour second shell, 2s1. It has one valence electron. It has actually one electron inits outermost shell. What about sodium? Well, sodium is walk to have the same electron configuration together neon, and then it's going to walk 3s1, so as soon as again, it hasone valence electron, one electron in that is outermost shell. So every one of these elementsin orange appropriate over here, they have actually one valence electron, and they're do the efforts toget come the octet rule, this type of secure nirvana because that atoms, and also so you can imagine isthat they're very reactive, and when castle react, they have tendency to lose this electron in the outermostshell, and that is the case. This alkali metalsare very very reactive, and actually, castle havevery comparable properties. They're shiny and soft, and also actually, since they're therefore reactive, it's hard to find them wherein they haven't reaction with various other things. Well, let's save lookingat the various other groups. Well, if we move one over to the right, this team two ideal over here, these are referred to as thealkaline planet metals. Alkaline, alkaline earth metals. And also once again, lock havevery comparable properties, and also that's because theyhave 2 valence electrons, two electrons in your outermost shell, and likewise for them, not quite as reactive together the alkali metals, yet let me write this,alkaline planet metals, however for castle it's easierto lose two electrons than to try to acquire six to get to eight, and so these often tend to alsobe sensibly reactive, and they react by losingthose two outer electrons. Now something interestinghappens together you walk to the D-block, and also we studied this when we looked in ~ electron configurations, yet if you look at theelectron construction for say, scandium best over here, the electron, allow me execute it in magenta, the electron configuration for scandium, so scandium, scandium's electron construction is walking to it is in the very same as argon, it's walking to be argon. The aufbau principle would tell united state that the electron configuration, us would have the 4s2 as with calcium, yet by the aufbau principle, us would additionally have one electron in 3d. So it would be argon, climate 3d1 4s2. And to acquire things in theright order because that our shells, allow me put the 3d1 prior to the 4s2. And so when human being thinkabout the aufbau principle, castle imagine all of these d-block elements as somehow pour it until it is full the d-block. Currently as we understand in various other videos,that's not precisely true, but when you're conceptualizingthe electron construction it could be useful. Climate you come over right here andyou start filling the p-block. So for example, if you lookat the electron configuration for, let's to speak carbon, carbon is walking to have actually thesame electron configuration together helium, together helium, and also then you're going tofill her s-block 2s2, and also then 2p one 2. For this reason 2p2. So how countless valenceelectrons does it have? Well, in its 2nd shell,its outermost shell, it has two add to two, ithas 4 valence electrons, and also that's walk to it is in truefor the points in this group, and because the that, carbon has comparable bondingbehavior to silicon, to the other things in its group. And we can keep going on, girlfriend know, because that example, oxygen, oxygen and also sulfur, these would both wantto take 2 electrons from someone else because theyhave six valence electrons, they desire to obtain to eight, therefore they have comparable bonding behavior. You go to this yellowgroup appropriate over here, these are the halogens. Therefore there's a one-of-a-kind name for them. These space the halogens. And also these are extremely reactive, since they have actually seven valence electrons. They would love nothing an ext than to acquire one more valence electron, therefore they love to react, in fact, they specifically love come react v the alkali metals over here. And also then finally, you acquire tokind of your atomic nirvana in the noble gases here. And also so the noble gases,that's the various other name because that the team 18 elements, noble gases. And also they all have actually thevery comparable property of no being reactive.


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Why don't lock react? They have filled their outermost shell. Castle don't discover the need, they're noble, they're type of above the fray, lock don't uncover the require tohave to react through anyone else.