VSEPR

Question 1

What is VSEPR used for?

Answer 1

Predicting the geometry of main group compounds with attached ligands

Question 2

What can VSEPR not be used for?

Answer 2

Transition metals

Question 3

What is the first step of VSEPR?

Answer 3

Decide on the connectivity of the molecule

Question 4

Which atom is always the central one?

Answer 4

the least electronegative one

Question 5

What is the second step of VSEPR?

Answer 5

Draw a lewis structure for the molecule and ignore the lone pairs

Question 6

What is the third step of VSEPR?

Answer 6

Count the electrons in pairs in the valence shell of the central atom

Question 7

How do we count the electrons in the valence shell of the central atom?

Answer 7

• Count its own valence shell electrons (the group number)
• Add one electron for every atom that is σ bonded to the central atom
• Add or subtract the appropriate number of electrons corresponding to any charge
• Account for any multiple bonds

Question 8

What is the 4th step of VSEPR?

Answer 8

Put all the electron pairs as far apart as possible using the vertices of the possible shapes

Question 9

What are the characteristics of linear shape?

Answer 9

2 pairs

2 directions 180 degrees

Question 10

What are the characteristics of trigonal planar?

Answer 10

3 pairs

3 angles at 120 degrees

Question 11

What are the characteristics of tetrahedral?

Answer 11

4 pairs

4 directions at 109.5 degrees

Question 12

What are the characteristics of trigonal bipyramidal?

Answer 12

5 pairs

Angles 90, 120 and 180 degrees between directions

Question 13

What are the characteristics of octahedral?

Answer 13

6 pairs

Angles of 90 and 120 degrees

Question 14

What are the characteristics of pentagonal bipyramidal?

Answer 14

7 pairs

Angles of 72, 90 and 180 degrees

Question 15

Why do multiple bonds repel more than single bonds?

Answer 15

They contain more electrons

Question 16

What is the order of repulsions?

Answer 16

LP-LP > LP-BP > BP-BP

Question 17

Why do lone pairs need more space than bonding pairs?

Answer 17

The attractive electrostatic force is weaker and the electron density can expand

Question 18

What position do multiple bonds and lone pairs occupy in the case of 5 pairs and why?

Answer 18

Equatorial

Equatorial positions have more space than axial

Question 19

How are the bonds and lone pairs arranged in octahedral?

Answer 19

Two lone pairs or multiple bonds are placed trans to each other

Question 20

How many BP and LP does linear have?

Answer 20

2 BP

0 LP

Question 21

How many BP and LP does trigonal planar have?

Answer 21

3 BP

0 LP

Question 22

How many BP and LP does bent/angular have?

Answer 22

2 BP

1 LP

Question 23

How many BP and LP does Tetrahedral have?

Answer 23

4 BP

0 LP

Question 24

How many BP and LP does Pyramidal have?

Answer 24

3 BP

1 LP

Question 25

How many BP and LP does bent have?

Answer 25

2 BP | 2 LP

Question 26

How many BP and LP does tbp have?

Answer 26

5 BP | 0 LP

Question 27

How many BP and LP does psuedo-tbp have?

Answer 27

4 BP | 1 LP

Question 28

How many BP and LP does T-shaped have?

Answer 28

3 BP | 2 LP

Question 29

How many BP and LP does linear with 5 electron pairs have?

Answer 29

2 BP | 3 LP

Question 30

How many BP and LP does octahedral have?

Answer 30

6 BP | 0 LP

Question 31

How many BP and LP does square pyramidal have?

Answer 31

5 BP | 1 LP

Question 32

How many BP and LP does square planar have?

Answer 32

4 BP | 2 LP

Question 33

What four things need to be considered when adjusting angles from their ideal values to their actual?

Answer 33

1. Lone pairs 2. Multiple bonds 3. Differences in electronegativity 4. Differences in size

Question 34

What do you do for each atom considered to be double bonded to the central atom?

Answer 34

Subtract 1 electron

Question 35

What do you do for each atom considered to be triply bonded to the central atom?

Answer 35

Subtract 2