Provide the complex ion structure and geometry when a Ni atom ...

Question

Provide the complex ion structure and geometry when a Ni atom combines with 2 chloro anions and 2 water molecules.

Accepted Answer

So here we need to provide the complex ion structure and geometry when a nickel atom combines with 2 chloroanions and 2 water molecules. Molecules. Alright. So let's do the complex ion structure first. Nickel atom. Atom means that it's in its neutral form because remember if it had a charge, we wouldn't use the term atom. We'd say ion. Also, if it had a charge, they would show it to us. Remember, transition metals have more than one charge. So if they're not giving you a charge, we're assuming that it's neutral. So we have neutral nickel. Sometimes you may see them write a 0 here to illustrate that it has no charge. We have 2 chloroanions, so that's 2 cl minus. And then we have 2 water molecules. Water is neutral. So our overall charge, we have 0 here, minus 2 from the 2 chlorines, plus 0 from the waters. So the complex ion should have a minus 2 charge overall. So the structure would be nickel. We write it in the order that's given to us. So we have nickel, we have 2 chlorides and then we have 2 waters. We put that in parenthesis and then the 2 on the outside. Then the overall charge is minus 2, so this would be 2 minus for our complex ion structure. Now, we need to figure out its geometry. Going back to coordination numbers, we have 4 ligands attached to our nickel atom, 2 chloroanions in 2 waters. So remember, if your coordination number is 4, it kind of sucks because that means you could be either tetrahedral or square planar. Now, do you remember the type of electron configurations that determine which one we have? Well, remember, if you're if you have a tetrahedral geometry, that's because you have a d 10 electron configuration. And if you're square planar, that means you have a d 8 electron configuration. So we have to look at the transition metal and its electron configuration. Nickel here, if you look at your periodic table, remember nickel would be argon, 4 s 23d8. And it's in its neutral form so we don't have to worry about removing any electrons. So here, it is a d 8 electron configuration. Therefore, we should draw it as square planar or planar. So we're gonna have our nickel in the center. So if we have nickel in the center, it's connected to 2 chloros and 2 waters. Now, there's 2 different ways you could draw this. So remember, with square planar, we have these 2 as being into the page of the paper and then these two bonds that point out of the plane of the paper. There's 2 different ways I could draw this square planar. So let's say I decided to draw the 2 chlorines being on the same side with each other. So they're both going into the paper. And then I drew the 2 water molecules as also being on the same side. Here we put brackets and the outside charge. So, remember what do we say if things are on the same side? Well, if you're on the same side, then you would be cis. So, this would be a cis configuration for this square planar structure. But let's say they're not on the same side. Let's say they're on opposite sides. So I put chlorine on opposite sides where one is going into the plane of the paper and one is pointing out of the plane of the paper. And the same thing with the water molecules. We put brackets and the charge on the outside. So what do we say if you're on opposite sides? Well, if you're on the same side, you're a cis. If you're on opposite sides, you are trans. So here, both are potential answers for the way to draw the geometry of this particular complex ion. So remember, when it has a coordination number of 4, it gets tricky because it could be either tetrahedral or square You have to look at the electron configuration of the transition metal to determine which one is favored. A d10 electron configuration gives us tetrahedral whereas a d 8 electron configuration gives us square planar. Alright. Now, I want you guys to attempt to do this practice question left at the bottom of the page. I'll give you guys a hint. We're gonna say here that we have Cobalt 3 ion connecting to 3 ethylenediamines. Ethylenediamine is an l two ligand. It has two sites where lone pairs can attach to our transition metals. Bidentate ligands, remember they make cyclic, complex ions. Also, because they have 2 sites of lone pair donation, it's kind of like counting it as 2 as 2 ligands. So, what I'm basically saying is, 3 ethylenediamine is equivalent to 6 ligands. Because each Ethylene Dimine is donating 2 lone pairs. So, 2 ligands per Ethylene Dimine. I'm telling you this hint because what kind of geometry do we have when we have 6 ligands involved? Okay. So that's all I'm gonna tell you. Attempt to see if you can draw this out. If you get stuck don't worry. Click on to the next video and see how I approach this practice question. Good luck guys.

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Provide the complex ion structure and geometry when a Ni atom combines with 2 chloro anions and 2 water molecules.

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