Electron Geometry (Simplified) - Video Tutorials & Practice Problems

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Electron Geometry is the simplest system for geometric shapes.

Electron Geometry

1

concept

Electron Geometry (Simplified) Concept 1

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So here we're going to say that the electron geometry represents the simplest system for geometrical shapes that focuses on the number of electrons groups around the central element. We're gonna stay here, we're gonna treat lone pairs and surrounding elements as the same. All right. So we can have 23 or four electron groups on the central element. So remember when you have two electron groups in the central element, that's just to surrounding elements. When we have three. Then there's two possibilities. We could have here. three Surrounding elements or to surrounding elements and one lone pair with four electron groups. There's multiple possibilities here, we're just showing two possibilities where it's four surrounding groups Or to surrounding groups in two lone pairs. Remember the one that I'm not showing that we talked about in earlier videos is you could have three surrounding elements and one lone pair as well. And that would still constitute a four electronic group structure. Now, the number of electrons groups determined the elect electron geometry when you have to surrounding groups. Your electron geometry is linear. So a good way to remember linear. Is that two points in a straight line. So two points to surrounding elements in a straight line, linear means a line when you have three electron groups. Then your electron geometry is tribunal or try donnell, planner or planner. So again, depending on where you are in the country, you might pronounce it differently. Tribunal planer, tribunal planner, Trigano planer, Trigano planner. It's all the same thing Here. A good way to remember. This is try equals three. It starts out with tri tri means 3 3 electron groups. Finally, if you're electron group is for the electron geometry is tetra federal. Good way to remember. Tetra hydro is. Tetra means four. Right. So tetra here means 44 electron groups. So when it comes to 23 and four electron groups, remember we have a linear tribunal planer and tetra hydro

The electron geometry of a compound treats surrounding elements and lone pairs on the central element as the same.

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example

Electron Geometry (Simplified) Example 1

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determine the electron geometry for the hydrogen sulfide molecule, or H two S. All right, so the electron geometry is based on your electron group number. If we take a look here, sulfur is connected to two lone pairs And two surrounding elements. Remember your electron group total equals lone pairs on the central element, plus the bonding groups on the central element, bonding groups meaning your loan on your surrounding elements. So we have two lone pairs and two surrounding elements. So our electron group is four. Tetra means four. So the electron geometry here will be tetra federal, so tetra hydro will be the shape for this hydrogen sulfide molecule.

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Problem

Problem

Determine the electron geometry for the carbon disulfide molecule, CS_{2}.

A

Linear

B

Bent

C

Trigonal planar

D

Tetrahedral

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example

Electron Geometry (Simplified) Example 2

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1m

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now recall there are many possible lewis dot structures that exist. But there are rules to draw the best structure here, we have to determine the electron geometry for the following molecule of CH two. Uh Alright, so here the number of valence electrons. We have carbon which is in group four a. We have hydrogen which is a group one a. And there's two of them And we have oxygen which is a group six a. Yeah, So that's 12 total valence electrons. We put carbon in the centre because remember hydrogen never goes in the center. Yeah, would form single bonds to the hydrogen into the oxygen initially we place enough electrons around the central elements so they follow the octet rule. But remember, hydrogen doesn't follow the octet rule. It follows the duet role. So it only needs a single bond and it's fine. At this moment we've used all 12 of our electrons. So there's not a lot. Remember bonding preferences, oxygen wants to make uh to bonds and carbon ideally wants to have four. So to accommodate both of them, we remove one of the lone pairs on oxygen and use it to make a double bond. So this would be the structure of our compound of CH 20, other, otherwise known as formaldehyde. Alright, so we'd say it has how many groups attached to it? The central element one, two, Three electron groups. Remember when you have three electron groups, three is try. So this is tribunal plane or planner. So this would be the electron geometry of the following compound.

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Problem

Problem

Determine the number of electron groups for the following cation:AsBr_{2}^{+}.