VSEPR Flashcards: Molecular Geometry & Bond Angles

Question 1

In VSEPR, what is an electron domain around a central atom?

Accepted Answer

A region of electron density: one bond to a neighboring atom, regardless of bond order, or one lone pair.

Question 2

What does the VSEPR model use to predict a central atom’s geometry?

Accepted Answer

Repulsion between electron domains. The domains favor an arrangement that reduces their mutual repulsion.

Question 3

In AXₙEₘ notation, what does A represent?

Accepted Answer

The central atom whose local geometry is being described.

Question 4

How do electron geometry and molecular geometry differ in VSEPR?

Accepted Answer

Electron geometry includes all electron domains. Molecular geometry describes the arrangement of atoms around the central atom, leaving lone pairs out of the shape name.

Question 5

How many VSEPR domains does one triple bond contribute at either bonded atom?

Accepted Answer

One domain. Three shared electron pairs occupy one bonding direction.

Question 6

In AXₙEₘ notation, what does n count?

Accepted Answer

Atoms directly bonded to the central atom. A double or triple bond still contributes one X.

Question 7

For a molecule with several central atoms, where do you apply VSEPR?

Accepted Answer

At each central atom separately, using its own bonded neighbors and lone pairs.

Question 8

In AXₙEₘ notation, what does m count?

Accepted Answer

Lone pairs on the central atom. E counts pairs, not individual electrons.

Question 9

For an AXₙEₘ center in the usual closed-shell VSEPR model, how many electron domains are present?

Accepted Answer

n + m domains: bonded neighbors plus lone pairs.

Question 10

VSEPR molecular shape of AX₂, with no lone pairs on A?

Accepted Answer

Linear. The two bonded atoms lie on opposite sides of the central atom.

Question 11

VSEPR molecular shape of AX₃, with no lone pairs on A?

Accepted Answer

Trigonal planar. The central atom and three bonded atoms lie in one plane.

Question 12

In an X–A–X bond angle, at which atom is the angle measured?

Accepted Answer

At A, the central atom, between the two bonds to X atoms.

Question 13

Does a lone pair count as one VSEPR domain or two?

Accepted Answer

One domain. The pair contains two electrons, but it occupies one region around the central atom.

Question 14

VSEPR molecular shape of AX₄, with no lone pairs on A?

Accepted Answer

Tetrahedral. The four bonded atoms occupy the corners of a tetrahedron around A.

Question 15

VSEPR molecular shape of AX₂E?

Accepted Answer

Bent, also called angular or V-shaped. There are two bonded atoms and one lone pair around A.

Question 16

What is the ideal X–A–X bond angle in AX₂ with no lone pairs?

Accepted Answer

180°.

Question 17

What electron geometry does VSEPR assign to three domains around a central atom?

Accepted Answer

Trigonal planar.

Question 18

VSEPR molecular shape of AX₃E?

Accepted Answer

Trigonal pyramidal. Three bonded atoms and one lone pair occupy four electron domains.

Question 19

What is the ideal X–A–X bond angle in tetrahedral AX₄?

Accepted Answer

About 109.5°.

Question 20

A central atom has two bonded neighbors and two lone pairs. What is its AXE notation?

Accepted Answer

AX₂E₂.

Question 21

What is the ideal X–A–X bond angle in trigonal planar AX₃?

Accepted Answer

120°.

Question 22

VSEPR molecular shape of AX₂E₂?

Accepted Answer

Bent, also called angular or V-shaped. Two lone pairs occupy the other two domains.

Question 23

What is the electron geometry around A in AX₃E?

Accepted Answer

Tetrahedral: three bonding domains plus one lone-pair domain.

Question 24

In O=C=O, how many electron domains surround carbon?

Accepted Answer

Two domains. Each C=O double bond counts once.

Question 25

What is the electron geometry around A in AX₂E?

Accepted Answer

Trigonal planar: two bonding domains plus one lone-pair domain.

Question 26

What molecular shape does VSEPR predict around carbon in CH₄?

Accepted Answer

Tetrahedral. Carbon has four bonded neighbors and no lone pairs.

Question 27

A learner counts a double bond as two VSEPR domains. What should they correct?

Accepted Answer

Count it as one domain. Bond order changes the number of shared electrons, not the number of bonded directions.

Question 28

What molecular shape does VSEPR predict around nitrogen in NH₃?

Accepted Answer

Trigonal pyramidal. Nitrogen has three bonded neighbors and one lone pair.

Question 29

What electron geometry does VSEPR assign to four domains around a central atom?

Accepted Answer

Tetrahedral.

Question 30

What molecular shape does VSEPR predict around oxygen in H₂O?

Accepted Answer

Bent. Oxygen has two bonded neighbors and two lone pairs.

Question 31

What molecular shape does VSEPR predict around carbon in the carbonate ion, CO₃²⁻?

Accepted Answer

Trigonal planar. The three C–O bonding directions give three domains, even when a Lewis structure shows one double bond.

Question 32

In the simple VSEPR model, how does a central lone pair usually affect neighboring bond angles?

Accepted Answer

It tends to compress nearby bond angles because its electron density occupies more space near the central atom. This is a qualitative tendency, not a fixed number of degrees.

Question 33

A VSEPR center is trigonal pyramidal with four total domains. What is its AXE notation?

Accepted Answer

AX₃E: three bonded atoms and one lone pair.

Question 34

Which two common AXE cases give a bent molecular shape with three or four total domains?

Accepted Answer

AX₂E with three domains, and AX₂E₂ with four domains. Their electron geometries differ.

Question 35

What electron geometry does VSEPR assign to five domains around a central atom?

Accepted Answer

Trigonal bipyramidal.

Question 36

What electron geometry does VSEPR assign to six domains around a central atom?

Accepted Answer

Octahedral.

Question 37

Does an ideal VSEPR angle give the exact measured angle in every molecule of that shape?

Accepted Answer

No. It is a geometric benchmark; lone pairs and the bonding environment can change actual angles.

Question 38

How many axial and equatorial positions are in a trigonal bipyramid?

Accepted Answer

Two axial positions and three equatorial positions.

Question 39

VSEPR molecular shape of AX₅, with no lone pairs on A?

Accepted Answer

Trigonal bipyramidal.

Question 40

VSEPR molecular shape of AX₆, with no lone pairs on A?

Accepted Answer

Octahedral.

Question 41

VSEPR molecular shape of AX₄E in the usual lowest-repulsion arrangement?

Accepted Answer

Seesaw. The lone pair occupies an equatorial position in a trigonal-bipyramidal domain arrangement.

Question 42

In an ideal trigonal bipyramid, what is the angle between two equatorial bonds?

Accepted Answer

120°.

Question 43

VSEPR molecular shape of AX₃E₂ in the usual lowest-repulsion arrangement?

Accepted Answer

T-shaped. Both lone pairs occupy equatorial positions.

Question 44

VSEPR molecular shape of AX₅E?

Accepted Answer

Square pyramidal. One lone pair occupies the sixth position of an octahedral domain arrangement.

Question 45

In an ideal trigonal bipyramid, what is the angle between an axial bond and an equatorial bond?

Accepted Answer

90°.

Question 46

VSEPR molecular shape of AX₂E₃ in the usual lowest-repulsion arrangement?

Accepted Answer

Linear. Three equatorial lone pairs leave the two bonded atoms in opposite axial positions.

Question 47

VSEPR molecular shape of AX₄E₂ in the usual lowest-repulsion arrangement?

Accepted Answer

Square planar. Two opposite lone pairs leave four bonded atoms in a square around A.

Question 48

In a trigonal-bipyramidal domain arrangement, which sites do lone pairs preferentially occupy?

Accepted Answer

Equatorial sites, in the usual VSEPR arrangements with one to three lone pairs.

Question 49

Which X–A–X angles occur in an ideal octahedral AX₆ molecule?

Accepted Answer

90° between adjacent bonds and 180° between opposite bonds.

Question 50

A VSEPR center has a seesaw shape and five total domains. What is its AXE notation?

Accepted Answer

AX₄E.

Question 51

A VSEPR center has a T-shaped molecular geometry and five total domains. What is its AXE notation?

Accepted Answer

AX₃E₂.

Question 52

In an ideal trigonal bipyramid, what is the angle between its two axial bonds?

Accepted Answer

180°. The axial positions lie on opposite sides of the central atom.

Question 53

A VSEPR center is square pyramidal with six total domains. What is its AXE notation?

Accepted Answer

AX₅E.

Question 54

In the usual octahedral AX₄E₂ arrangement, how are the two lone pairs positioned relative to each other?

Accepted Answer

Opposite each other, 180° apart in the ideal domain arrangement.

Question 55

What molecular shape does VSEPR predict for an isolated SF₄ molecule?

Accepted Answer

Seesaw. Sulfur has four bonded fluorine atoms and one lone pair.

Question 56

What molecular shape does VSEPR predict for an isolated XeF₂ molecule?

Accepted Answer

Linear. Xenon has two bonded fluorine atoms and three lone pairs.

Question 57

What is the electron geometry around A in AX₃E₂?

Accepted Answer

Trigonal bipyramidal: three bonding domains plus two lone-pair domains.

Question 58

What molecular shape does VSEPR predict for an isolated BrF₅ molecule?

Accepted Answer

Square pyramidal. Bromine has five bonded fluorine atoms and one lone pair.

Question 59

What molecular shape does VSEPR predict for an isolated XeF₄ molecule?

Accepted Answer

Square planar. Xenon has four bonded fluorine atoms and two opposite lone pairs.

Question 60

What is the electron geometry around A in AX₄E?

Accepted Answer

Trigonal bipyramidal: four bonding domains plus one lone-pair domain.

Question 61

What molecular shape does VSEPR predict for an isolated ClF₃ molecule?

Accepted Answer

T-shaped. Chlorine has three bonded fluorine atoms and two equatorial lone pairs.

Question 62

What is the electron geometry around A in AX₅E?

Accepted Answer

Octahedral: five bonding domains plus one lone-pair domain.

Question 63

What is the electron geometry around A in AX₂E₃?

Accepted Answer

Trigonal bipyramidal: two bonding domains plus three lone-pair domains.

Question 64

What molecular shape does VSEPR predict for an isolated SF₆ molecule?

Accepted Answer

Octahedral. Sulfur has six bonded fluorine atoms and no lone pairs.

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