Topic 2- Bonding, Structure and the Properties of Matter

Question 1

What is ionic bonding?

Answer 1

Ionic bonding is the electrostatic attraction between positive and negative ions (oppositely charged)

It is a relatively strong attraction

metals combined with non metals

Question 2

How are ionic compounds held together?

Answer 2

They are held together in a giant lattice

It is a regular 3D structure that extends in all directions in a substance

Electrostatic attraction between positive and negative ions holds the structure together

Question 3

What does ionic bonding consist of?

Answer 3

Its when electrons in the outer shell of the metal atom are transferred

Metal atoms lose electrons to become positively charged ions

Non-metal atoms gain electrons to become negatively charged ions

Question 4

State properties of ionic substances

Answer 4

High melting and boiling points (due to strong electrostatic forces between oppositely charged ions)

Do not conduct electricity when solid (ions in fixed positions)

Conduct electricity only when molten or dissolved in water (ions are free to move)

Question 5

What is a covalent bond?

Answer 5

Covalent bond is a shared pair of electrons between two atoms

Question 6

Describe the structure and properties of simple molecular covalent substances

Answer 6

• Do not conduct electricity (no ions)
• Small molecules
• Weak intermolecular forces and therefore, low melting and boiling points

Question 7

How do intermolecular forces change as the mass/size of the molecule increases?

Answer 7

They increase. That causes melting/boiling points to increase as well (more energy needed to overcome these forces)

Question 8

What are polymers?

Answer 8

They are large covalently bonded molecules

Intermolecular forces between polymer molecules are relatively strong and so these substances are solids at room temperature

Question 9

What are giant covalent substances?

Answer 9

Solids, atoms covalently bonded together in a giant lattice

High melting/boiling points - strong covalent bonds

Mostly don’t conduct electricity (no delocalised electrons)

Diamond, graphite, silicon dioxide

Question 10

Describe and explain the properties of diamond

Answer 10

Four, strong covalent bonds for each atom.

It is very hard (due to strong bonds)

Very high melting point (due to strong bonds)

Does not conduct electricity (no delocalised electrons)

Question 11

Describe and explain the properties of graphite

Answer 11

Three covalent bonds for each carbon atom

Layers of hexagonal rings

High melting point

Layers free to slide due to weak intermolecular forces and no covalent bonds between layers

Soft, can be used as a lubricant

Conducts thermal and electricity due to one delocalised electron per carbon atom

Question 12

Describe and explain the properties of fullerenes

Answer 12

Hollow shaped molecules

Based on hexagonal rings but can also contain rings with five or seven carbon atoms

Question 13

Describe and explain the properties of nanotubes

Answer 13

They are cyclindrical fullerenes with very high length to diameter ratios

High tensile strength (strong bonds)

Conductivity (deloc. electrons)

Question 14

Describe and explain the properties of graphene

Answer 14

Single layer of graphite

Has properties that make is useful in electronics and composites

Graphene is very strong because atoms within its layers are very tightly bonded

It is also elastic because the planed of atoms can flex relatively easily without the atoms breaking apart

Question 15

What are some of the uses of graphene and fullerenes?

Answer 15

They can be used as lubricants, to deliver drugs in the body and catalysts

Nanotubes can be used for reinforcing materials, for example tennis rackets

Question 16

What is metallic bonding?

Answer 16

Forces of attraction between delocalised electrons and nuclei of metal ions

Question 17

Describe properties of metals

Answer 17

High melting/boiling points (strong forces of attraction)

Good conductors of heat and electricity (deloc. electrons)

Malleable, soft (layers of atoms can slide over each other whilst maintaining the attraction forces)

Question 18

What are alloys and why are they harder than pure metals?

Answer 18

Mixtures of metal with other elements which are usually metals

Different sizes of atoms distorts the layers, so they can’t slide over each other meaning they are harder than pure metals

Question 19

What are fine and coarse particles?

Answer 19

Fine particles (soot), 100-2500 nm diameter

Coarse particles (dust) 2500-1,000,000 nm diameter

Question 20

Explain why graphite is soft and is a good conductor of electricity

Answer 20

Each atoms forms 3 covalent bonds
This forms layers
Layers can slide over each other
Delocalised electrons

Question 21

Why do carbon nanotubes conduct electricity?

Answer 21

They contain delocalised electrons

Electrons can move through the structure

Question 22

Give one limitation of using a dot and cross diagram to represent a molecule

Answer 22

It is two dimensional

Question 23

Why does ammonia have a low boiling point?

Answer 23

Small molecules

Weak intermolecular forces

Less energy needed to break down

Question 24

A student added copper metal to colourless silver nitrate solution

The student observed:

• pale grey crystals forming
• the solution turning blue

Explain how these observations show that silver is less reactive than copper

Answer 24

The crystals are silver

The copper ions are blue

This is because copper displaces silver

Question 25

A student is given 3 metals, XYZ

They must be identified

The metals are magnesium, iron and copper

Plan an investigation to identify the three metals by comparing their reactions with dilute hydrochloric acid

Answer 25

Add metals to hcl

Measure temp change

Copper-no reactions shown by no temp change

Magnesium and Iron: Mg increases in temp more than iron

Must keep mass of metal and conc of hcl the same

Question 26

Explain why graphite is:

• A good electrical conductor
• Soft and slippery

Answer 26

• Giant covalent structure
• Each carbon atom forms 3 bonds (1 spare bond)
• C bonded in hexagonal layers
• delocalised electrons
• Electrons free to move between layers
• Relatively weak interactions/forces of attraction

Question 27

Explain why sodium oxide high melting point

Answer 27

• Giant ionic structure
• Lots of strong bonds between ions
• Lots of energy required to overcome

Question 28

What has intermolecular forces?

Answer 28

Graphite

Simple covalent structures

Nothing else!