Equatorial and Axial Positions

covalin compounds with five or six electron groups have equatorial and axial positions for their surrounding elements. Now when we say the equatorial position, we're gonna say the equatorial position. These are your surrounding elements position around the equator of a compound. So here we. Take a look at these two illustrations, we can say that the equator of this sphere is right here And here we have five electron groups. Three of them are along the equator here we have six electron groups and four of them are along the equator of the sphere. Now, if we say axial or ethical position, this is basically a surrounding elements position above or below the equatorial position. So remember we have our equator here. So our actual positions are above it, or below it and here above it or below it. Now these arrangements themselves, they increase repulsion between elements. This in turn causes a decrease in energy for the compounds. And just remember in chemistry, if we decrease our energy, that's a good thing that leads to greater stability. Now, a rule of thumb is we're gonna say that the more electro negative element tends to prefer the actual position over the equatorial position. Okay, so this again ties into the whole idea of energy and stability. So just remember these fine points when we're talking about five electron group molecules and six electron group molecules

based on your knowledge of actual and equatorial positions draw the most likely structure of pF two cl three. Alright. So remember when it comes to drawing lewis dot structures, we place the least electro negative element in the senate in this case would be phosphorus mhm phosphorus has attached to it, five bonding groups to florian's and three chlorine. So it's a five electron group system. Now, phosphorus and group five. So this makes sense. Remember that three of them would be along the equator and two of them would be in the actual positions. Now remember in terms of stability and energy, we want the more electro negative element to be in the actual positions. Flooring is more electro negative than chlorine. So flooring replacing the actual positions. So remember Florence in group 78. So it only has seven valence electrons, hala jeans like chlorine and flooring when they're not in the center, they only make single bonds as surrounding elements. And then we draw the chlorine chlorine zone, Group 70 as well. So they have seven valence electrons. Then he were drawing them. Here they are along the equator. So this would be the most stable most likely structure of pF two Cl three. We have a five Elektron system and therefore we have equatorial axial positions. Flooring is more electro negative in chlorine. Remember flooring would go into the axial positions and chlorine. We will go into the equatorial positions

lone pair positions are extremely important when trying to draw the most accurate molecule here, we're going to say that lone pairs will orient themselves in order to decrease the interactions between surrounding elements. Now here when we're drawing different structures were paying more attention to those with six electron groups and those with five electron groups were going to say here that with six electron group systems, lone pairs are most stable in the actual position. Within five electron group systems, lone pairs are most stable in the equatorial position. Now you might ask, how do I remember this? Well we have a memory toll for that and the memory tool is just remember. It's a long as long as you remember the hands of the clock. So if we take a look here at the first clock, we have the hands giving us a time of 6:00. Now let's just imagine that that circle in the middle, that dark circle represents our central element. And here this would represent our equator. We're going to say, We said when it deals with six electron groups, they are in the actual positions. So remember actual positions are straight up and straight down. So above and below the equator of our structure. And if we look they're pointing at 6:00. So we're gonna say 6:00 is for six electron groups. The hands are pointing straight up and straight down just like actual positions point straight up and straight down for five electron group systems. Again, we imagine that we have our equator here. Both the hands are not pointing straight up and straight down so they wouldn't represent actual positions. They represent equatorial positions. So here we say that five o'clock is 45 electron groups. Alright, so just remember, you can remember six o'clock straight up and straight down. Those are actual positions. And you remember lone pairs are most stable in the actual positions. If it's at five o'clock, that means both hands are not straight up and straight down so they couldn't be actual positions. They would be equatorial positions. So in those cases lone pairs or should be oriented in the equatorial positions to draw the best possible structure. So keep that in mind when we deal with five electron group systems and six electron group systems.

for this example question it says determine the molecular geometry of the following ion. So here we're dealing with S. c. l. three negative. Alright so here we're gonna place sulfur as our central element Sulfur itself is in group six a. So it has six valence electrons. And here it's gonna use three under the six To make connections to our three florins Chlorine are in group seven a. So they each have seven valence electrons. They use one of their electrons to make a single bond to our sulfur atom. And we're going to say this is what our structure would look will look like. So the chlorine have used all their electrons available, sulfur has only used three out of its six total electrons. So here we're gonna draw its remaining three. Now we're gonna go back and clean this up based on our understanding of five electron systems versus six electron systems. So right now let's just draw the basic framework of our structure. So there goes five valence electrons and here's the 6th -1 means we've gained an outside electron. The chlorine no longer need an extra electron. They're all making them right amount of bonds that they want. So that extra electron that we're gaining because it's -1 it's going to go to the sulfur. And because our structure has a charge we need to draw it in brackets with the charge on the outside. Now we need to determine is this a five elektron system or a six electron system. Well if we look we're going to say that we have one two 345 electron groups. So this is a five electron group system. So think about our memory tool. It's a lock as long as you remember the hands of the clock. So five groups means we're looking at 5:00. Both hands are pointing straight up or straight down. So they're not in the actual position, they'd be in the equatorial position. That means our loan pairs should be oriented in the equatorial position to draw the best possible structure. So here we're gonna play sulfur in the center. So we're gonna draw the correct structure over here, sulfur goes in the center, the two lone pairs that it has, we have to draw them in the equatorial position. And one of the Koreans will also be in the equatorial position as well. So there it goes. Okay and then the other two are gonna be in the axle positions pointing straight up and straight down. Okay, So there goes our structure. Now remember draw this one as our extra electron. Remember because this structure has a charge and put it in brackets with the charge on the outside. So this would be the correct way of drawing SCL three negative. Right? So just remember when you're dealing with the 6th electron group system or five electron group system, it's important to remember. Where should my lone pairs go knowing that gives you the best possible structure