VSEPR Flashcards

1
Q

What is the Valence Shell Electron Pair Repulsion Theory?

A
  • It is a way to predict covalent bonded 3D structures based on the fact that electron pairs/domains will want to be as far away from each other as possible
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2
Q

What does a Lewis Structure show?

A
  • Shows atom to atom connectivity
  • Shows distibution of valence electrons
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3
Q

What does a VSEPR Structure show?

A
  • Translates Lewis into molecular geometry
  • Helps predict the shape and bond angles of molecules
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4
Q

What does a wedge show?

A

Coming out of the page

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5
Q

What does a Hash show?

A

Going into the page

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6
Q

What does a line show?

A

In the same plane as the paper

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7
Q

What is an electron domain?

A
  • Regions in space where valence electron density can be found
  • Lone Pairs
  • Bonds (a single, double, or triple bond all count as one domain)
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8
Q

What is an Electron-pair Geometry?

A
  • Describes the arrangement of all electron pairs/domains around a central atom in 3D Space
  • Includes bonds and lone pairs
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9
Q

What is a Molecular Geometry Shape?

A
  • Describes the arrangement of bonding pairs/domains around a central atom in 3D space
  • Shape the bonds make
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10
Q

If a central atom has only bonding domains…

A

Electron-pair geometry = molecular shape

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11
Q

If a central atom has both bonding domains and lone pairs…

A

Electron-pair geometry does not = molecular shape

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12
Q

What does the presence of lone pairs have on bond angles?

A

Decreases bond angles because lone pairs like to have more space

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13
Q

What are the characteristics of a 2-electron domain - Linear Electron-Pair geometry?

A
  • All atoms lie in a straight line
  • The bond angle between three atoms is 180 degrees
  • No non-bonding electrons on the central atom
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14
Q

What are the characteristics of a 3-electron domain - Trigonal Planar Electron-Pair geometry?

A
  • A central atom is surrounded by 3 atoms
  • All atoms can lie in the same plane
  • The bond angle is 120 degrees
    (consider resonance)
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15
Q

What are the characteristics of a 3-electron domain - Trigonal Planar Electron-Pair geometry with a bent molecular shape?

A
  • A central atom is bonded by 2 atoms and has 1 lone pair
  • All atoms can lie in the same plane
  • The bond angle are < 120 degrees
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16
Q

What are the characteristics of a 4 Electron Domain - Tetrahedral Electron-Pair geometry?

A
  • A central atom is bonded to 4 atoms
  • The bond angles are 109.5 degrees
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17
Q

What are the characteristics of a 4 Electron Domain - Tetrahedral Electron-Pair Geometry with a Trigonal Pyramidal Molecular Shape?

A
  • A central atom is bonded to 3 atoms and has 1 lone pair
  • The bond angles are <109.5 degrees
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18
Q

What are the characteristics of a 4 Electron Domain - Tetrahedral Electron-Pair Geometry with a Bent Molecular Shape?

A
  • A central atom is bonded to 2 atoms and has 2 lone pairs
  • The bond angles are «109.5 degrees
19
Q

What are the characteristics of a 5 Electron Domains - Trigonal Bipyramidal Electron-Pair geometry?

A
  • A central atom is bonded to 5 atoms
  • The bond angles are 120 degrees and 90 degrees or 180 degrees
20
Q

What are the characteristics of a 5 Electron Domains - Trigonal Bipyramidal Electron-Pair geometry with a Seesaw Molecular Shape?

A
  • A central atom is bonded to 4 atoms and has 1 lone pair
  • The bond angles are <90 degrees and <120 degrees
  • The lone pair electrons occupies an equatorial position (because there is more space)
21
Q

What are the characteristics of a 5 Electron Domains - Trigonal Bipyramidal Electron-Pair geometry with a T-shaped molecular Shape?

A
  • A central atom is bonded to 3 atoms and has 2 lone pairs
  • The bond angles are <180 degrees and <90 degrees
  • The lone pair electron occupies two of the equatorial positions
22
Q

What are the characteristics of a 5 Electron Domains - Trigonal Bipyramidal Electron-Pair geometry with a Linear Molecular Shape?

A
  • A central atom is bonded to 2 atoms and has 3 lone pairs
  • The bond angles are 180 degrees
  • The lone pairs occupy all of the equatorial positions
23
Q

What are the characteristics of a 6 Electron Domains - Octahedral Electron-Pair Geometry with a Square Pyramidal Molecular Shape?

A
  • A central atom is bonded to 5 atoms and has 1 lone pair
  • The bond angles are <90 degrees between adjacent atoms
  • The bond angles are <180 degrees between opposite atoms
  • Lone pair electrons occupy an axial atom position
24
Q

What are the characteristics of a 6 Electron Domains - Octahedral Electron-Pair Geometry?

A
  • The central atom is bound to 6 atoms
  • The bond angles are 90 degrees between adjacent atoms
  • The bond angles are 180 degrees between opposite atoms
25
Q

What are the characteristics of a 6 Electron Domains - Octahedral Electron-Pair Geometry with a Square Planar Molecular Shape?

A

A central atom is bonded to 5 atoms and has 1 lone pair
- The bond angles are 90 degrees between adjacent atoms
- The bond angles are 180 degrees between opposite atoms
- Lone pair electrons occupy the axial atom position

26
Q

What is the Axial position?

A

Axial positions refer to any two opposite vertices along a straight line through the center of the molecule

27
Q

What is the Equatorial Position?

A

Equatorial positions refer to locations around the central atom that lie in the plane of the molecule

28
Q

What is the bond angle for a Linear?

A

180 degrees

29
Q

What is the bond angle for a Trigonal Planar?

A

120 degrees

30
Q

What is the bond angle for a Bent Trigonal Planar

A

<120 Degrees

31
Q

What is the bond angle for a Tetrahedral

A

109.5 degrees

32
Q

What is the bond angle for a Trigonal Pyramidal Tetrahedral?

A

<109.5 degrees

33
Q

What is the bond angle for a Bent Tetrahedral?

A

«109.5

34
Q

What is the bond angle for a Trigonal Bipyramidal?

A

120 degrees and 90 degrees or 180 degrees

35
Q

What is the bond angle for a Seesaw Trigonal Bipyramidal?

A

<90 degrees and <120 degrees

36
Q

What is the bond angle for a T-shaped Trigonal Bipyramidal?

A

<180 degrees and <90 degrees

37
Q

What is the bond angle for a Linear Trigonal Bipyramidal?

A

180 degrees

38
Q

What is the bond angle for an Octahedral?

A

90 degrees between adjacent atoms and 180 degrees between opposite atoms

39
Q

What is the bond angle for a Square Pyramidal Octahedral?

A

<90 degrees between adjacent and <180 degrees between opposite atoms

40
Q

What is the bond angle for a Square Planar Octahedral?

A

90 degrees between adjacent atoms and 180 degrees between opposite atoms

41
Q

How do you draw VSEPR diagrams for larger molecules?

A
  • Atom connectivity
  • Draw the best lewis structure
  • How many electron domains
  • What is the geometry and shape around each central atom
  • Bond angles
  • Try to draw the most in the plane of the page
42
Q

If you remove an electron in the 5 Electron domain where is it removed from?

A

Equatorial atoms

43
Q

If you remove an electron in the 6 Electron domain where is it removed from?

A

Axial atoms