Structure 2.4 Flashcards

1
Q

Alloy properties

A

Lower melting points, less malleable/ductile, harder, less directional bonding

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1
Q

Alloys

A

A mixture of more than one metal

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2
Q

Polymer

A

A repeating chain of monomers held together by covalent bonds

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3
Q

Monomer

A

Individual repeating units in a polymer

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4
Q

Monomers joint in addition reactions

A

Addition polymer and condensation reactions - don’t form byproducts

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5
Q

Thermoplastics

A

Soften when heated and harden when cooled, recyclable

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6
Q

Thermosetting plastics

A

Change irreversibly into hardened thermosets and cannot be recycled

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7
Q

Elastomers

A

Polymers that are flexible and can be reformed under a force but will return to the original shape when stress is released

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8
Q

Bonding triangle

A

Shows the three extreme types of bonding plotted against the difference in electronegativity and the change in electronegativity

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9
Q

Ionic bond

A

Electrostatic attractions between two oppositely charged ions

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10
Q

Covalent bond

A

The electrostatic attraction between the nuclei of two atoms and their valence electrons, sharing of electrons

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11
Q

Metallic bonds

A

The electrostatic attraction between the cations and sea of delocalised valence electrons

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12
Q

When does a solid melt?

A

When attractive forces between particles are overcome and particles are free to move

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13
Q

What is melting point influenced by?

A

The way in which particles pack in the solid state

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14
Q

Ionic compounds conductivity

A

Don’t conduct in solid state but conduct when molten or in aqueous liquid

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15
Q

Why do ionic compounds (molten/in aqeous) decompose when conducting?

A

As conductivity is due to movement of electrons

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16
Q

Conductivity of allotropes of non metals

A

Usually good as they have delocalised electrons

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17
Q

Elasticity

A

The ability of a material to resist a distorting influence and return to original when force is removed

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18
Q

Metals elasticity

A

Elastic as atoms can easily slide over each other in the lattice

19
Q

Polymer elasticity

A

Can be stretched without being permanently broken so are elastic

20
Q

Covalent solid brittleness

A

Very brittle as bonds cannot be reformed once broken

21
Q

Metals brittleness

A

Very malleable as layers of atoms can slide over each other

22
Q

Ionic solid brittleness

A

Very brittle as ionic lattice breaks without being deformed when sufficient force is applied

23
Q

Addition polymers

A

Formed from alkenes and no other product are produced, a carbon to carbon double bond is broken

24
Q

100% atom economy

A

All reactant becomes product

25
Q

Condensation reaction

A

Water will be produced in addition to the condensation product

26
Q

What is needed to form a condensation polymer?

A

Two functional groups (can be same or different) so that once the condensation product in formed, it can continue reacting with two functional groups

27
Q

Ester link

A

One monomer has two carboxlic acid groups, one monomer has two alcohol groups (-COOH, -OH)

28
Q

Polyester

A

A polyester is made by a reaction involving an acid with two carboxlic groups, and an alcohol with two alcohol groups.

29
Q

What happens when a monomer with two carboxylix acid and one monomer with two amine groups react?

A

A polyamide is formed

30
Q

Aminde link

A

When a monomer with two carboxylix acid and one monomer with two amine group react, an aminde link forms (-COOH, -NH2)

31
Q

Polyamide can also be formed…

A

By condensing amines with either dicarboxlyic acids or with diacyl chlorides

32
Q

Kevlar

A

Condensation polymer and also example of a polyamide

33
Q

Why is kevlar so strong?

A

Because it consists of rigid rod shaped molecules that are cross linked by intramolecular hydrogen bonding between the chains

34
Q

When does kevlar lose its protective properties?

A

In concentrated sulfric acid solution, the O and N atoms in the amide linkage become prononated and break down

35
Q

Biological macromolecules

A

Condensation polymers

36
Q

Amino acids

A

Building blocks of proteins, have a carboxyl group and an amino group bonded to the same carbon atom

37
Q

Peptide bond

A

Amide bond amino acids form

38
Q

Polysaccharides

A

Many sugar units condensed together

39
Q

Hydrolysis

A

Reverse reaction of condensation

40
Q

Alloy

A

Mixture of more than one metal

41
Q

Properties of an alloy

A

Lower melting point, harder, more brittle

42
Q

What can polymers form and how?

A

Addition polymers through addition reactions, condensation polymers and polysaccardies through condensation reactions

43
Q

Thermoplastics

A

Can be remoulded when heated

44
Q

Thermosetting

A

Changes irreversibly in soft solid/viscous state

45
Q

Elastomers

A

Flexible polymers that can return to original shape

46
Q

Delocalised pi electron

A

An electron shared between two or more nuclei, found in all resonance structures