topic 7- structures (inc ionic, giant covalent, simple covalent, polymers and metals)

Question 1

Features of giant covalent structures

Answer 1

• high melting point
• no specific formula
• 1 large molecule

Question 2

Ball and stick diagrams

(i) this component represents bonds between atoms
(ii) this component represents atoms

Answer 2

(i) stick

(ii) ball

Question 3

Why do giant covalent structure ps have very high melting points?

Answer 3

As they have very strong covalent bonds between the atoms

Question 4

Why is diamond hard?

Answer 4

It has lots of strong covalent bonds

Question 5

Why doesn’t diamond conduct electricity?

Answer 5

It has no delocalised electrons in its structure

Question 6

Why does diamond have a high melting point?

Answer 6

A lot of energy is needed to break the strong covalent bonds. Therefore it has a high melting point

Question 7

In diamond, each carbon atom is bonded to __ other carbon atoms by strong covalent bonds

Answer 7

4

Question 8

What is carbon?

Answer 8

A giant covalent structure

Question 9

What shape are the carbon atoms in graphite’s layers?

Answer 9

Hexagonal (6-sided)

Question 10

Graphite has ____ intermolecular forces keeping layers together

Answer 10

Weak

Question 11

Why is graphite very soft?

Answer 11

It’s layers can easily slide over one and another

Question 12

In graphite, each carbon atom is bonded to __ other carbon atoms by strong covalent bonds

Answer 12

3

Question 13

Why can graphite conduct electricity?

Answer 13

• each carbon atoms forms three bonds
• this means that there is a delocalised electron from every carbon atom
• this electron can move freely, therefore graphite is a good electrical conductor

Question 14

What are fullerenes?

Answer 14

Molecules of carbon atoms that take up hollow structures. Their structure is usually carbon atoms arranged in hexagonal (6-sided) rings, but pentagonal (5-sided) and heptagonal (7-sided) carbon rings can also be found.

Question 15

What type of molecule is buckminsterfullerene?

Answer 15

A simple molecule because of its fixed size

Question 16

What shape is the buckminsterfullerene?

Answer 16

Spherical

Question 17

What is the formula for buckminsterfullerene?

Answer 17

C60

Question 18

Common uses of spherical fullerenes:

Answer 18

• catalysts
• lubricants
• as vehicles for transporting drugs into our bodies

Question 19

Carbon nanotubes are…

Answer 19

Cylindrical fullerenes

Question 20

Why are carbon nanotubes exceptionally strong for their size?

Answer 20

because of strong covalent bonds between carbon atoms

Question 21

uses of cylindrical fullerenes:

Answer 21

• in electronics
• in nanotechnology
• for strengthening materials (e.g. tennis racket frames)

Question 22

Carbon nanotubes are often called molecular wires, why?

Answer 22

As they have a tiny diameter but can be incredibly long

Question 23

Why does graphene conduct electricity?

Answer 23

Graphene is a single layer of graphite so it also conducts electricity because of the carbon atoms’ delocalised electrons

Question 24

Why is graphene light?

Answer 24

It has a thickness of just 1 atom. This means it’s almost a two dimensional structure and so graphene is very light

Question 25

Why is graphene very strong?

Answer 25

It has strong covalent bonds between carbon atoms

Question 26

What are graphene’s uses?

Answer 26

Graphene has lots of uses in electronics and composite materials >graphene makes materials stronger without making them much heavier >graphene can be used in solar panels, batteries and so much more

Question 27

What are polymers?

Answer 27

Large chain-like molecules that can extend for thousands of atoms.

Question 28

Polymers are held together by...

Answer 28

- weak intermolecular forces between molecules | - strong covalent bonds between atoms in molecules

Question 29

What state are polymers usually at room temperature?

Answer 29

Solid

Question 30

Why do the intermolecular forces in polymers add up to be quite strong?

Answer 30

Because of the large size of polymer molecules

Question 31

Why do many polymers melt easily?

Answer 31

The intermolecular forces between molecules remain less strong than chemical bonds

Question 32

What does the ‘n’ in the bottom right of a polymer diagram tell us?

Answer 32

How many times the unit is repeated to create the larger polymer molecule

Question 33

When polymers undergo addition ____, poly(propene) is the product

Answer 33

-polymerisation

Question 34

Why are pure metals soft and malleable?

Answer 34

Because the ions are arranged in layers, they easily move over each other when a force is applied

Question 35

Why do pure metals have high melting and boiling points?

Answer 35

There are strong electrostatic forces between metal ions and delocalised electrons

Question 36

What are metals made up of?

Answer 36

Giant structures of regularly arranged atoms

Question 37

What is the structure of pure metals?

Answer 37

A regular lattice of positive ions, cations, in a ‘sea’ of delocalised electrons

Question 38

Delocalised electrons are...

Answer 38

-not bound to an atom and are free to move around within the lattice

Question 39

When does delocalisation happen?

Answer 39

When metal atoms have a small amount of electrons in their outer shells

Question 40

Which would a metallic bonding be found in: - sodium (Na) - sodium chloride (NaCl)

Answer 40

-sodium (Na)

Question 41

Why are metals good conductors of electricity and heat?

Answer 41

Because their delocalised electrons can carry a charge/ heat throughout the structure. The electrons move from the negative terminal to the positive terminal

Question 42

Which bonds have 2 atoms sharing 1 or more pairs of electrons and are found in most non-metal compounds?

Answer 42

Covalent

Question 43

Which bonds involve an attraction between positive ions and negative, delocalised electrons

Answer 43

Metallic

Question 44

What is an ionic bond formed from?

Answer 44

An attraction between a negatively charged ion (anion) and a positively charged ion (cation)

Question 45

What forces hold together an ionic lattice?

Answer 45

Electrostatic forces

Question 46

What is the empirical formula of C7H4O2?

Answer 46

C7H4O2

Question 47

What type of bonding involves the movement of electrons from one atom to another?

Answer 47

Ionic

Question 48

What is happening during freezing?

Answer 48

Molecules are losing energy, moving around less and forming a fixed lattice

Question 49

Which of these is a property of ionic compounds: (i) can conduct electricity while solid (ii) cannot conduct electricity when molten (iii) have high melting points

Answer 49

(iii) have high melting points

Question 50

which molecule has a higher boiling point: (i) chlorine (ii) sucrose

Answer 50

(ii) sucrose

Question 51

Which of the following can conduct electricity? - NaCl(aq) - diamond - polythene - graphite

Answer 51

-NaCl(aq) and Graphite

Question 52

What is the charge on a carbonate ion?

Answer 52

2-

Question 53

How many double bonds and single bonds are there in a carbonate ion?

Answer 53

Number of single bonds= 2 | Number of double bonds= 1

Question 54

Why do electrons become delocalised in metals?

Answer 54

Because the electron orbitals in the metal atoms overlap

Question 55

Displacement reactions

Answer 55

When a more reactive metal (one that forms positive ions more easily) can displace a less reactive metal from a compound