Organic Chemistry And Carbon Bonding

Question 1

Why is Carbon so important?

Answer 1

Carbon has the ability to bind strongly to other elements and to form strong bonds to itself

Carbon is central to organic chemistry

Question 2

What is the ground-state configuration of Carbon?

Answer 2

Putting electrons into its lowest state orbitals

C has 6 protons and hence 6 electrons and a mass of 12

Question 3

How many unpaired electrons does Carbon have?

Answer 3

2 unpaired electrons

If carbon remained in ground state when forming covalent bonds, it would only form 3 bonds and only have 6 electrons in its outer shell

Question 4

What is an example of covalent bonding in Carbon?

Answer 4

Methane

C
H
H
H
H

Question 5

What is another example of covalent bonding in Carbon?

Answer 5

Ethane

C
H
H
H

Question 6

Atomic Orbital Theory for Carbon

Answer 6

• S orbital can contain up to 2 electrons
• Each set of P orbitals can contains up to 6 electrons (3x2)
• Each set of D orbitals can contain up to 10 electrons (5x2)
• Each set of F orbitals can contain up to 14 electrons (7x2)

Question 7

What is an In-Wave? M.O.T:

Answer 7

• constructive influence
• peaks and troughs are alligned
• produces region of highest probability of electron density
• wave produced with greater amplitude

Question 8

What is an outer wave? M.O.T:

Answer 8

• destructive influence
• opposite shape to each other
• produces a wave with less/no amplitude

Question 9

Dimensions of waves in orbitals:

Answer 9

• waves are three dimensional
• combine with in-phase waves producing regions with a higher probability of electron density and out-of-phase waves producing nodes, or regions of no electron density

Question 10

What are bonding orbitals?

Answer 10

Electrons in a (os/in-phase) orbital are attracted by both nuclei at the same time and are more stable (of lower energy) than in isolated atoms. Adding electrons to these orbitals creates a force that holds the two nuclei together.

Question 11

In phase orbitals produced:

Answer 11

OS
- lower energy molecular orbital
- electron density directly between the nuclei
- bonding orbitals

Question 12

Out-of-phase orbitals produced:

Answer 12

O*S
- higher energy molecular orbital
- node between the nuclei’
- antibonding orbital

Question 13

What is hybridisation?

Answer 13

Concept of mixing atomic orbitals form new hybrid orbitals suitable for the pairing of electrons to form chemical bonds in valence bond theory

Question 14

Hybridisation of carbon process (sp^3) :

Answer 14

-promote a 2s electron into a 2p orbital, creating 4 orbitals of equal energy
- energy recovered from promotion by forming bonds
- carbon can now form 4 covalent bonds
-gives 8 electrons in outer shell = stable
Hybrid model is energetically favoured

Question 15

What are organic molecules:

Answer 15

Organic molecules are usually composed of carbon atoms in rings or long chains, to which are attached other atoms of elements such as hydrogen, oxygen and nitrogen.

Question 16

Organic molecules/ no. Of carbon atoms:

Answer 16

1-methane
2-ethane
3-propane
4-butane
5-pentane
6-hexane
7-heptane
8-octane
9-nonane
10-decane
11-undecane
12-Dodecane

Question 17

What shape is an sp3 hybrid orbital?

Answer 17

• electrons in different orbitals repel each other
• if carbon forms 4 bonds to hydrogen atom, mutual repulsion will push the molecular orbitals as far apart as possible
• results in a tetrahedral arrangement, maximises distances of electrons in each of the bonds
  Methane (CH4) tetrahedral, 109.5 bond angle

Question 18

Ethane sp2 orbital:

Answer 18

• flat shape
• 120 bond angle
• sp2 orbitals form o-bonds by overlap with s-orbitals of hydrogen and sp2 orbitals of carbon

Question 19

What is an o bond?

Answer 19

End-on overlap- more effective C-C o-bond
Stronger, less reactive

Question 20

What is a pi bond?

Answer 20

Edgewise overlap- less effective
C=C pi-bond
Weaker; more reactive

Question 21

Sp geometry:

Answer 21

4 atomic orbitals positioned as far apart as possible
- hybrid orbitals form the o-framework
- unhybbridsed p-orbitals give the pi-bonds
P/SP orbital bond angle- 90
SP/SP orbital bond angle- 180

Question 22

Draw complex organic molecules (ethane):

Answer 22

sp3 hybridised: tetrahedral 109.5 degree bond angles

Question 23

Draw complex organic molecule ethene:

Answer 23

Sp2 hybridised: trigonal 120 degree bond angles

Question 24

Draw complex organic molecule ethyne:

Answer 24

Sp hybridised: linear 180 degree bond angles

Question 25

What are cycloalkanes?

Answer 25

Formed when 3 to 7 carbon atoms occur in a ring structure rather than a linear one. In a ring structure less hydrogen atoms are required than in an alkane
The general molecular formula is CnH2n

Question 26

What do the functional groups do?

Answer 26

The functional groups of an organic molecule determine its properties and its reactivity

Question 27

What are the organic functional groups?

Answer 27

Carbon-containing functional groups
- alkane
- alkene
- alkyne
- arene