5. VSEPR & Molecular Shapes (Test 3 )

Question 1

What will be the molecular geometry for a molecule with a central atom that has five regions electron density if one of the regions of electron density is a lone pair?

Answer 1

seesaw

Question 2

According to VSEPR theory, electrons in the valence shell of a central atom form __________.

Answer 2

both lone pairs and bonding pairs of electrons

Question 3

What is the electron-pair geometry and molecular structure of ammonia (NH3)?

Answer 3

tetrahedral, trigonal pyramidal

With four electron domains, the electron-pair geometry must be tetrahedral. With one lone pair, the molecular geometry must therefore be trigonal pyramidal.

Question 4

A trigonal planar molecule will have bond angles of __________.

Answer 4

120 degrees

Question 5

The number of electron domains surrounding an atom will determine the:

Answer 5

electron-pair geometry

Question 6

What is the molecular structure of SnCl−3?

Answer 6

trigonal pyramidal

SnCl−3 has four electron regions with one resulting from a nonbonding pair. The electron pair geometry is tetrahedral, and the molecular structure is trigonal pyramidal.

Question 7

Which spatial orientation will involve more than one bond angle value?

Answer 7

trigonal bipyramidal

Trigonal bipyramidal geometry will exhibit both 120∘ and 90∘ bond angles.

Question 8

the angle between any two bonds that include a common atom, usually measured in degrees.

Answer 8

bond angle

Question 9

the distance between the nuclei of two bonded atoms along the straight line joining the nuclei

Answer 9

bond distance

Question 10

enables us to predict the molecular structure of a molecule, including approximate bond angles around a central atom, from an examination of the number of bonds and lone electron pairs in its Lewis structure.

Answer 10

Valence shell electron-pair repulsion theory (VSEPR theory)

Question 11

Two regions of electron density around a central atom in a molecule form a

180 degrees

Answer 11

linear geometry

Question 12

three regions of electron density around a central atom in a molecule form a

120 degrees

Answer 12

trigonal planar geometry

Question 13

four regions of electron density around a central atom in a molecule form a

109.5 degrees

Answer 13

tetrahedral geometry

Question 14

five regions of electron density around a central atom in a molecule form a

90 and 120 degrees

Answer 14

trigonal bipyramidal geometry

Question 15

six regions of electron density around a central atom in a molecule form a

90 and 90 degrees

Answer 15

octahedral geometry

Question 16

Which electron-pair geometry involves fewer than five regions of electron density and a 180∘ bond angle?

Answer 16

linear

Question 17

Which of the following allows us to predict the molecular structure?

Answer 17

VSEPR theory

Question 18

The R in VSEPR theory stands for

Answer 18

repulsion

Question 19

What is the electron pair geometry of SnCl−3?

Answer 19

tetrahedral

SnCl−3 has four electron regions with one resulting from a nonbonding pair. The electron pair geometry is tetrahedral (4), and the molecular structure is trigonal pyramidal.

Question 20

What will be the molecular structure of the ammonium ion (NH+4)?

Answer 20

tetrahedral

Nitrogen will have four electron domains, all of which are bonds, so both the geometry and structure will be tetrahedral.

Question 21

molecular structure of NH+4

Answer 21

tetrahedral

Question 22

What is the electron pair geometry of IF5?

Answer 22

octahedral

IF5 has six electron domains with one of those domains resulting from a nonbonding pair. The electron pair geometry is octahedral (6), and the molecular structure is square pyramidal because the lone pair occupies an equatorial position to minimize lone pair repulsions.

Question 23

What will be the electron-pair geometry of XeF2?

Answer 23

trigonal bipyramidal

With five domains, two being bonds and three being lone pairs, the electron-pair geometry must be trigonal bipyramidal.

Question 24

What is the molecular structure of SF4?

Answer 24

see-saw

SF4 has five electron domains with one resulting from a nonbonding pair. The electron pair geometry is trigonal bipyramidal (5), and the molecular structure is seesaw because the the nonbonding pair will occupy a equatorial position.

Question 25

The ________ describes the location of electrons and the ________ describes the location of atoms.

Answer 25

electron-pair geometry, molecular structure

Question 26

A molecule with three electron regions where one is a lone pair will have _____ molecular geometry.

Answer 26

bent or angular

Question 27

Bond angles decrease as more lone pairs are added because

Answer 27

lone pairs repel other electron densities slightly more than bonding pairs

Question 28

A molecule with square planar geometry but with six electron regions has ______ lone pairs.

Answer 28

2

A molecule with square planar geometry but with six electron regions has two lone pairs. Square planar molecular structure accounts for four bonding pairs. If there are six total electron dense regions, and four are taken up by those bonding pairs, then the remaining two will be lone pairs. These lone pairs will occupy the positions that are opposite from one another in order to accommodate the greater repulsion, giving rise to the square planar geometry.

Question 29

Lone pairs present in trigonal bipyramidal electron-pair geometry always occupy which position?

Answer 29

equatorial

Question 30

The V in VSEPR theory stands for __________.

Answer 30

valence

Question 31

Lewis structures are limited because they do not display the __________.

Answer 31

correct bond angles in the molecule

Question 32

In which molecule are the electron-pair geometry and molecular shape of the same type?

Answer 32

CO2

Carbon dioxide has both linear electron-pair geometry and molecular shape, whereas the others have at least one lone electron pair on the central atom, which makes the molecular shape different than the electron pair geometry.

Question 33

The structure that includes only the placement of the atoms in the molecule is called

Answer 33

molecular structure

Question 34

naming the geometry that includes all electron pairs the

Answer 34

electron-pair geometry

Question 35

The electron pair geometry is the same as the molecular structure when there is/are _______ lone pair(s) around the central atom.

Answer 35

0

Question 36

A molecule with linear geometry but five electron regions has ______ lone pairs.

Answer 36

3

A molecule with linear geometry but five electron regions has three lone pairs. Linear geometry accounts for two bonding pairs. If there are five total electron dense regions and two are taken up by bonding pairs, then the remaining three must be by lone pairs.

Question 37

A molecule with four electron regions where two are lone pairs has which geometry?

Answer 37

bent or angular

Question 38

If a molecule with octahedral electron-pair geometry contains a central atom with two lone pairs, what will be the resulting molecular geometry?

Answer 38

square planar

Question 39

Which pair of electron domains generates the most repulsion?

Answer 39

lone pair-lone pair

Question 40

which molecule will have a net dipole?

Answer 40

SO2

Question 41

When the absolute value of the difference in electronegativity of two bonded atoms is very small or zero, the bond is:

Answer 41

covalent and nonpolar