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Question 1

How do molecular orbitals form?

Answer 1

Molecular orbitals form when atomic orbitals combine

Question 2

What happens to the molecular orbitals in non-polar covalent bonds?

Answer 2

In a non-polar covalent bond, the bonding molecular orbital is symmetrical about the
midpoint between two atoms

Question 3

What happens to the molecular orbitals in polar covalent bonds?

Answer 3

Polar covalent bonds result from bonding molecular orbitals that are asymmetric about the midpoint between two atoms

Question 4

What does the combining of two atomic orbitals form?

Answer 4

The combination of two
atomic orbitals results in the formation of a bonding molecular orbital and an antibonding
orbital

Question 5

What does the bonding molecular orbital encompass?

Answer 5

encompasses both nuclei.

Question 6

What does the antibonding molecular orbital have?

Answer 6

Has higher energy arrangement and are normally empty but they can be occupied when the bonding orbitals are full or the electron is excited to a higher energy.

Question 7

How are sigma bonds formed?

Answer 7

Molecular orbitals that form by end-on overlap of atomic orbitals along the axis of the
covalent bond

Question 8

How are pi bonds formed?

Answer 8

Molecular orbitals that form by side-on overlap of parallel atomic orbitals that lie
perpendicular to the axis of the covalent bond

Question 9

What is hybridisation?

Answer 9

Hybridisation is the process of mixing atomic orbitals within an atom to generate a set of new atomic orbitals called hybrid orbitals. These hybrid orbitals are degenerate

Question 10

What contains sp3 hybridisation?

Answer 10

single bonds between atoms

Question 11

What is sp3 hybridisation

Answer 11

the 2s orbital and the three 2p orbitals of carbon hybridise to form four degenerate sp3 hybrid orbitals

Question 12

What contains sp2 hybridisation?

Answer 12

double bonds between atoms

Question 13

What is sp2 hybridisation

Answer 13

The 2s orbital and two of the 2p orbitals hybridise to form three degenerate sp2 hybrid orbitals

Question 14

What contains sp hybridisation?

Answer 14

triple bonds between atoms

Question 15

What is sp hybridisation

Answer 15

The 2s orbital and one 2p orbital of carbon hybridise to form two degenerate hybrid orbitals

Question 16

How do electrons fill molecular orbitals?

Answer 16

Electrons fill bonding molecular orbitals, leaving higher energy antibonding orbitals unfilled

Question 17

What does HOMO stand for?

Answer 17

The highest bonding molecular orbital containing electrons is called the highest occupied molecular orbital (HOMO)

Question 18

What does LUMO stand for?

Answer 18

The lowest antibonding molecular orbital is called the lowest unoccupied molecular orbital (LUMO)

Question 19

How does colour arise in molecular orbitals?

Answer 19

Absorption of electromagnetic energy can cause electrons to be promoted from HOMO to LUMO.

Question 20

What are chromophores?

Answer 20

A chromophore is a group of atoms within a molecule that is responsible for absorption of light in the visible region of the spectrum. Light can be absorbed when electrons in a chromophore are promoted from the HOMO to
the LUMO.

Question 21

What are conjugated systems?

Answer 21

Electrons within this conjugated system are delocalised. Molecules with alternating single and double bonds, and aromatic molecules have conjugated systems

Question 22

What does more conjugated systems result in?

Answer 22

the smaller the energy gap between HOMO and
LUMO. A lower frequency of light (longer wavelength, lower energy) is absorbed by the
compound. When the wavelength of light absorbed is in the visible region, the compound
will exhibit the complementary colour

Question 23

What does less conjugated systems result in?

Answer 23

The greater the energy gap between the HOMO and the LUMO.