(a) molecular orbitals

Question 1

Can VESPER explain the bonding in all compounds?

Answer 1

No

Question 2

What, other than VESPER, can provide an explanation for complex molecules?

Answer 2

Molecular orbital theory

Question 3

When do molecular orbitals form?

Answer 3

When atomic orbitals combine

Question 4

What is the relationship between the number of molecular orbitals that are formed and the number of atomic orbitals which are combined?

Answer 4

They are equal

Question 5

What does the combination of two atomic orbitals result in?

Answer 5

A bonding and an anti-bonding orbital

Question 6

Where are the nuclei situated in molecular orbitals?

Answer 6

Both are found in the bonding molecular orbital.

Question 7

What is the basis of the bonding between atoms?

Answer 7

The attraction between the positively charged nuclei and the negatively charged electrons.

Question 8

What is the maximum number of electrons per molecular orbital?

Answer 8

2

Question 9

What is the bonding molecular orbital in a non-polar covalent bond?

Answer 9

Symmetrical, about the mid-point between the 2 atoms.

Question 10

What is the bonding molecular orbital in a polar covalent molecule?

Answer 10

Asymmetrical about the 2 midpoint between 2 atoms.

Question 11

What atom has the greater share of the bonding electrons?

Answer 11

The atom with the greater electronegativity.

Question 12

What is a case of extreme asymmetry?

Answer 12

Ionic compounds

Question 13

Where are the bonding molecular orbitals in an ionic compound?

Answer 13

Almost entirely located around one atom.

Question 14

What does extreme asymmetry result in?

Answer 14

The creation of ions.

Question 15

What kind of atomic orbital overlap occurs in sigma bonds?

Answer 15

End-on

Question 16

What kind of atomic overlap occurs in pi bonds?

Answer 16

Side-on

Question 17

How can carbons bonding and shape be deciphered?

Answer 17

Hybridisation

Question 18

What is hybridisation?

Answer 18

The process of mixing atomic orbitals within an atom to generate a set of new atomic orbitals called hybrid orbitals.

Question 19

What is the energy said to be in hybrid orbitals?

Answer 19

Degenerate

Question 20

In alkanes the 2s orbitals and the 2p orbitals of the carbon hybridise to form what?

Answer 20

Degenerate sp3 hybrid orbitals

Question 21

What shape is adopted by the sp3 hybrid orbitals?

Answer 21

Tetrahedral

Question 22

How do the sp3 molecules overlap with other atomic orbitals?

Answer 22

End-on

Question 23

What does the end on overlap of sp3 molecules with other atomic orbitals produce?

Answer 23

sigma bonds.

Question 24

What can the bonding of 2 alkenes be described as?

Answer 24

sp2 hybridisation

Question 25

What do the 2s orbitals and 2p orbitals hybridise to form?

Answer 25

sp2 hybrid orbitals

Question 26

What shape do sp2 hybrid orbitals adopt?

Answer 26

Trigonal planar

Question 27

How do sp2 orbitals overlap and what do they form?

Answer 27

End-on to form sigma bonds

Question 28

What happens to the remaining 2p orbital on each carbon?

Answer 28

Remains unhybridised and lies perpendicular to the axis of the pi bond.

Question 29

How do the remaining 2p orbitals overlap and what do they form?

Answer 29

Side-on to form pi bonds

Question 30

How can the bonding of benzene and other aromatic systems be described?

Answer 30

sp2 hybridisation

Question 31

What bond is between the carbon atoms in a benzene ring?

Answer 31

Sigma and pi

Question 32

What structure does a benzene ring have?

Answer 32

Cyclical

Question 33

What can the electrons in a benzene ring be described as?

Answer 33

Delocalised

Question 34

How can the bonding between alkynes be described?

Answer 34

sp hybridisation

Question 35

(sp) What do the 2s orbital and 2p orbital hybridise to form?

Answer 35

Two degenerate hybrid orbitals.

Question 36

What arrangement do the 2 degenerate hybrid orbitals adopt?

Answer 36

Linear

Question 37

How do the hybrid sp molecules overlap and what do they form?

Answer 37

End-on to form sigma bonds.

Question 38

What happens to the 2 remaining 2p orbitals (sp)?

Answer 38

The overlap side on to form 2 pi bonds.

Question 39

How else can molecular orbital theory be used?

Answer 39

To explain why organic molecules are colourless or coloured.

Question 40

What orbital do electrons fill up first?

Answer 40

Bonding molecular orbitals.

Question 41

What orbital is left unfilled?

Answer 41

Anti-bonding molecular orbitals.

Question 42

What is the highest bonding molecular orbital containing electrons called?

Answer 42

Highest Occupied Molecular Orbital (HOMO)

Question 43

What is the lowest anti bonding molecular orbital called?

Answer 43

Lowest Unoccupied Molecular Orbital (LUMO)

Question 44

An absorption of electromagnetic energy can cause what?

Answer 44

Electrons to be promoted from HOMO to LUMO.

Question 45

Why do most organic molecules appear colourless?

Answer 45

The energy difference between HOMO and LUMO is relatively large.

Question 46

What does a large difference between HOMO and LUMO result in?

Answer 46

The absorption of light from the ultraviolet region of the spectrum.

Question 47

What do some organic molecules contain?

Answer 47

Chromophores.

Question 48

What is a chromophore?

Answer 48

A group of atoms within a molecule that is responsible for absorption of light in the visible region of the spectrum.