Coordination Numbers & Geometry - Video Tutorials & Practice Problems
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1
concept
Coordination Numbers
Video duration:
27s
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When it comes to the co-ordination number, it represents the number of ligands or ligands bonded to the central metal cion. And we're gonna say the most common numbers for our coordinations are 24 and six. And as we start looking at coordinations complexes and more deeply into the complex ions that they have, we'll have a better image and a better look at the coordinations that are involved.
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example
Coordination Numbers and Geometry Example
Video duration:
51s
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Here it says, determine the co-ordination number of the complex ion. Remember all together this repre represents our coordinating complex. The complex ion is just the portion that is in brackets. So let's bring that down. So in brackets, we have our chromium connected to four waters and two bromide ions. So here is our metal cion. Our co-ordination number is based on the number of ligands or ligands attached to it. If we take a look, that's four waters and two bromide ions. So in total, that's six ligands or ligands, which gives us a coordinating number of six. So six would be our final answer.
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concept
Molecular Geometry of Coordination Complexes
Video duration:
2m
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Now, we can say that coordinations complexes form predictable geometries based on either their coordinations number or their electron configuration. And we're gonna say with the coordinations number of four, that's when you must determine the metal CS electron geometry. So if you don't have a coordinating number of four, then it's pretty straightforward. And we take a look here, remember our coordinations that are possible are 24 and six at least in terms of this level of gen chem. When we have a coordinations of two, that means we have two lider ligands attached to my metal cion. Here we have an example of a complex ion that's formed. Its geometry would be linear and a memory tool to help us remember is two points in a straight line, two ligands or ligands helped to make a linear a line in terms of geometry. If you have a co ordination number of six, that means you have six ligands or ligands attached to your metal cion. This would be octahedral. When you think of octahedral, you can think of octopus, but an octopus has eight tentacles, not six. So we just say eight tentacles here minus two eyes equals six for coordinating number. Now, here we finally get to co ordination numbers of four with co-ordination numbers of four. Just say that if we have for the metal cion, an electron configuration that ends with D 10, then we are tetrahedral. And if it end with D eight, then you are square planer. If we come back up here, tetrahedral, we have a zinc here with four hydroxides. Tetrahedral is drawn in this configuration. Remember we said if the metal cion has an electron configuration of ending with D 10, then it is tetrahedral. So D 10 10 is tente tetrahedral, they match together. If your metal cion ends with D eight, then it is square planar or square planar. One way to remember this is square has four sides. A plane has two wings, four times two, gives us eight D eight, right? So just use these little memory tools to help you remember when you have a coordinations of 24 and six to figure out the correct geometry for your particular complex.
4
example
Coordination Numbers and Geometry Example
Video duration:
30s
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Here, it says, determine the geometry for the following complex. Here, we have chromium and it's attached to four ammonia molecules and two chloride ions. Here, it really doesn't take much for us to realize that we have a total of six ligands connected to the chromium. Here, we don't have to worry about the charge of the chromium chromium or any of that. The fact that there are six ligands means that the geometry has to be octahedral. So that'd be the geometry for the following complex.
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Problem
Problem
Correctly label all the components of the coordination complex and its coordination number: Na2[SnCl6].
A
Sn2+: metal cation Cl–: ligands Na+: counterions
B
Sn2+: metal cation Cl–: counterions Na+: ligands
C
Sn2+: counterion Cl–: ligands Na+: metal cation
D
Sn4+: metal cation Cl–: ligands Na+: counterions
E
Sn4+: metal cation Cl–: counterion Na+: ligands
F
Sn4+: counterion Cl–: ligands Na+: metal cation
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Problem
Problem
Determine the geometry for the following complex ion: [Ni(OH)4]2–.
A
Tetrahedral
B
Square planar
C
Octahedral
D
Linear
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Problem
Problem
Determine the geometry for the following complex molecule: Pd(H2O)4.
A
Octahedral
B
Square Planar
C
Linear
D
Tetrahedral
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