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F335 Chemistry by Design: Colour by Design
Bonding and Structure

(a) explain the term electronegativity: recall qualitatively the electronegativity trends in the Periodic Table;
use relative electronegativity values to predict bond polarity in a covalent bond; decide whether a
molecule is polar or nonpolar from its shape and the polarity…

Page 2

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F335 Chemistry by Design: Colour by Design
These intermolecular forces are the weakest .
Permanent dipole The + and charges on polar molecules cause weak electrostatic forces of
­ permanent attraction between molecules, e.g. HCl (H is + and chlorine is ).
dipole These intermolecular forces are stronger than instantaneous…

Page 3

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F335 Chemistry by Design: Colour by Design

Organic Functional Groups

(d) recall that fats and oils consist mainly of mixed esters of propane1,2,3triol with varying degrees of
Triglycerides are the major constituent of fats and oils. They are esters formed from the condensation reactions
between glycerol and three fatty…

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F335 Chemistry by Design: Colour by Design

(ii) describe the delocalisation of electrons in these compounds

(iii) explain how delocalisation accounts for their characteristic properties [limited to undergoing
substitution (often slowly) rather than addition reactions]
Benzene undergoes substitution rather than addition reactions with electrophiles. By reacting in this way, the…

Page 5

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F335 Chemistry by Design: Colour by Design

Organic Reactions

(g) describe and explain the following electrophilic substitution reactions of arenes, naming the benzene
derivatives formed:
Type of Reagents and Reaction
Electrophilic Conditions
Halogenation ­ Bromination ­ Br 2(l) 1. The benzene molecule becomes polarised as it approaches the

Page 6

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F335 Chemistry by Design: Colour by Design
Heat under reflux
with dry either.

(h) describe and explain the formation of diazonium compounds and coupling reactions that these undergo
to form azo dyes
Azo compounds contain the ­N=N­ group. Compounds in which the R groups are arenes are
much more stable…

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F335 Chemistry by Design: Colour by Design

The oxygen in phenol and nitrogen in amine has lone pairs which increases the electron density of the benzene
ring ­ this gives the diazonium ion (weak electrophile) something to attack and be attracted to. Many different
azo compounds can be formed by…

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F335 Chemistry by Design: Colour by Design

(k) describe and explain the general principles of gasliquid chromatography:
(l) understand the techniques used to identify the materials used in a painting, including:
(i) gasliquid chromatography
(ii) atomic emission spectroscopy
(iii) visible spectroscopy (reflection and absorption)
and explain and predict given results…

Page 9

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F335 Chemistry by Design: Colour by Design
that lots of light is being absorbed . Therefore, the peaks of the
graph indicates the colour of the object.

Differences between Visible Infrared Spectra:
Vis peaks rise from the base line ­ shows radiation absorbed .
IR peaks hang down from base…


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