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General Chemistry

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23. Chemistry of the Nonmetals


The Halogens represent Group 7A of the periodic table. 

The Halogens

The Halogens represent the final group before we reach the barely reactive Noble Gases of Group 8A. 


The Halogens

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in this group. We're gonna go over the elements in Group seven A otherwise known as the Allergens. So here, guys, we're going to say that the halogen, the elements in Group seven A represent the last reactive group on the periodic table. That's because the next group are are noble gasses, Group eight A and for the most part, the majority. Those elements are non reactive in groups. Eight A. Now we're gonna say the halogen themselves exist as die atomic molecules. So we'll have have to c l to be our two i two and the less talked about asked a team, which is 82 now, the final slot in this group. It belongs Toa Tennessean, and from the name you can see that it's named after Tennessee, the state, and it was previously called a new on Sucked him. Remember on is one and cept refers to seven, so it's referring to the element on the periodic table with an atomic number of 17. Now, talking about some of the physical and chemical behaviors of this group, we're going to say the halogen is display very predictable physical properties. We're gonna say here because they're all die atomic molecules worth the same exact elements connected together. They're gonna share electrons equally when they're bonded to their copy. So they're non polar, meaning their inter molecular force is London dispersion or dispersion forces. Now, as we move down the group, we're going to see that there's gonna be an increase in this inter molecular force. So the strength of the inter molecular forces gonna get stronger and stronger, the low we go down the group that's gonna result in different, different physical features for these halogen. It's now here we're gonna not talk about asked 18 or Tennessee because they're radioactive, so they're highly unpredictable. So we're just gonna stick to the first four halogen flooring, chlorine, bromine and iodine. Now, what we should see here is, if we're looking our bond length as we go down the group bond length increases, we can see that the numbers are getting bigger and bigger. That's because as we go down a group, your atomic size increases. This causes an increase in your bond length, and we're gonna say here the relationship is as your bond length increases, so your bonds getting longer and longer. That means your bond is getting weaker. So weaker bonds as they increase in length. This results in a decrease in your bond energy. Okay, but we see exceptions to this rule. We see that all of a sudden that Floyd's number should have been much higher. It should've been a bigger number. Should have been a number greater than 243. So it should have been a number bigger than 2. 43. And it should have decreased as we go down, which is the normal progression that we should see because we just said if your bond links are increasing, then we expect our bond energies to decrease. Now, why exactly is F two at a lower bond energy than the others? Well, at least chlorine and growing. That's because F two, we're gonna say here that the florins in the bond are small, very, very electoral negative, and as a result, they repel each other. Yeah, okay. This causes the lowering of their bond energies less energy required to break them. So just imagine it has to flooring atoms because they're very electron negative. That's gonna force them to wanna come closer and closer to one another to come into contact with the others electrons. But if they get too close, what happens then is they get to close to one another, so they repel each other. As a result, their bond length is longer than it should be. And because their bond is longer than it should be, this results in a lower bond Energy. Now going back to the idea of saying as we go down the group, the Inter Molecular Forces increase. This has a direct impact on their physical features. Here, F to itself is a yellow gas or light yellow gas. Okay, so F two exists as a gas. Co two is also a gas. This one has a yellowish rhenish color. Okay, As we're going down, the inter molecular forces are increasing, which is gonna cause them to change phase, change physical states. So here, with BR to now be, our two is gonna exist as a liquid. Here. It looks like a brownish orange liquid. And then finally I too. I too is just a purple solid, a dark purple solid. Okay. And these changes in phase from gasto look with the solid is a result of inter molecular forces increasing as we go down the group Now, in terms of oxidation states, we're gonna say, remember, they're all in group seven. We know the most common charge for groups seven days minus one. So they're most common. Oxidation state is minus one. And we're gonna say all of the halogen, except for flooring, can obtain all odd number states for their oxidation numbers ranging from plus seven tu minus one. Meaning chlorine bromine or I die depending on what their next two could be. Plus seven plus five plus three plus one or minus one or zero for their charge or their oxidation number. We're going to stay here. Also, that halogen react eggs author Mickley with one another to form inter halogen compounds. So, for example, you could have, um, chlorine connecting toe flooring. Okay, so this is an inter halogen compound to different colleges connecting together. The less electro negative one will have an oxidation number off plus one. The Mawr electro negative one will have an oxidation number of minus one. That's the trend we need to see in terms off inter halogen compounds. Now, we're gonna say here that these halogen themselves can combine with oxygen to form hallow oxy and ions. Okay. And we're gonna say here that these oxy and ions they can be hypo. Highlights, Highlights, highlights and perhaps lights saw. Hypo Highlight. It has the form form of X O negative X equals flooring, chlorine, bromine or iodine. Our satellite, you add an additional oxygen. How late? At additional oxygen Per halle at an additional oxygen. So here, with flooring. The Onley form that exists for flooring when it comes to a hallow. Oxy an ion. Is this form F or minus? Okay, so this would be Hypo Floor, right? The other forms do not exist for it. And that has to do with the electro negative value and very small size of flooring. It's just not allowed to have those other forms for chlorine, chlorine can exist as Hi book Low right, which we know we can have. Cool, right Core rate and Pirkle rate. Okay, so that's Cielo to minus Cielo three minus Cielo four minus bro. Mean Broening itself can also have all of these different forms so we can have Hypo, Bro, might we can have hypo whole, right? We could have chlor eight. I mean, bromate actually in this hypo. Sorry, guys. This is Bromate, bro. Might This will be throw mate. And this will be per bromate. So this would be B r o minus B R o to minus B R 03 minus and B r 04 minus and then here for iodine. Iodine doesn't have ah highlight form, but it can have this form Io minus, which is height Boat. I owed ICT here. We could have I owe three minus, which is I owe date and then we can have I owe four minus, which is per io date. So these are the allowed hallow Occean ion forms of each of the halogen. It's now here we can say that in basic solutions Halogen is form hypo highlights and at elevated temperatures Um, it conform, Hal, it's so here we can see how a Hallett is form. For example, we can have br to liquid here to react with all h minus. To produce our bromate ion, we get a bromide ion in the process and water being produced here. We're not gonna worry too much about balancing just realizing that this is a possibility when it comes to reacting. These allergens in basic solutions. Basic solutions is how we come about and producing these hallow oxy and ions. So besides things that we've learned earlier about periodic trends of halogen thes are the key features you need to keep in mind when it comes to the different types of halogen within this group. Remember, asked a team and Tennessee, we don't really talk about them because the radioactive in nature, so they're hard to predict what they're going to do. For now, we're gonna say, when it comes to the hallow, oxy and ions as well, these are the forms you need to remember. Also, remember that once you add an H plus thio each one of these different Polly atomic ions, you're gonna make an oxy and ion or oxy acid, and that's in another chapter altogether. Remember, Oxy acids are important when we're talking about determining pH. When it comes to naming of acids. Just keep that in mind off the different forms that exist for each one of these challenges