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The
Materials
Revolution



Topic 2
Unit F334

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Electronegativity is the ability to attract the bonding electrons in a covalent bond


Atoms with strong electron pulling power in covalent bonds are said to be highly electronegative.

Fluorine is the most electronegative element.
Oxygen, nitrogen chlorine are also strongly electronegative.




In a covalent bond between two atoms of different…

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Whether a molecule has a permanent dipole depends on its shape and the polarity of its bonds.


1. In a simple molecule, like hydrogen bromide, the polar bond gives the whole molecule a permanent
dipole ­ it's a polar molecule.




2. A more complicated molecule may have several polar bonds.…

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Intermolecular forces are forces between molecules.
They are much weaker than covalent, ionic or metallic bonds.

Permanent Dipole ­ Permanent Dipole

Permanent dipoles occur when a molecule has two atoms bonded
together which have substantially different electronegativities so
that one atom attracts the shared electrons much more than the
other.…

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Amines are organic derivatives of ammonia .

Ammonia has three hydrogen atoms bonded to a central
nitrogen, whereas amines have one or more alkyl groups
substituted for hydrogen. Ammonia

Like ammonia, the lone pair of electrons on the nitrogen atom
is responsible for the three main properties of amines.

They…

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Solubility of Amines

Amines can form hydrogen bonds to water.
Because of this strong attraction between amine
molecules and water molecules, amines with small
alkyl groups are soluble.
Amines with larger alkyl groups are less soluble
because the alkyl groups disrupt the hydrogen
bonding in water.

Amines are Bases

A…

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Amines as Nucleophiles

Ammonia can act as a nucleophile with the lone pair of electrons on the N atom attacking
electrophiles, such as the positively polarised carbon atom in halogenoalkanes.

Primary amines react with halogenoalkanes to form secondary amines. A nucleophile is
an electron pair
The primary amine is acting…

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Amides contain the functional group: CONH2


Primary amide Secondary amide

RCONH2 RCONHR

Formed by the reaction of ammonia with Formed by the reaction of an amine with
an acyl chloride an acyl chloride



Hydrolysis of Amides

Hydrolysis means bond breaking through reaction with water.
When amides are hydrolysed, it is…

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A polymer is a long molecule made up from lots of small molecules called monomers.

Addition Polymerisation

Many polymers are formed in a reaction known as addition polymerisation.
The monomers usually contain C=C double bonds.
The double bonds open up and join together to make long chains called addition polymers.…

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Condensation Polymers

When an NH2 group reacts with the ­COOH group in a
carboxylic acid, a secondary amide group is formed, with the structure:



This type of reaction, in which two molecules react together to form a large molecule with the
elimination of a small molecule such as water is…

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