Unit 2 - Structures and Properties

Question 1

Name the 4 main structures that substances can have?

Answer 1

Simple Molecular

Giant Ionic

Giant Covalent

Giant Metallic

Question 2

What sort of molecules do simple molecular substances have? And an example?

Answer 2

Small molecules eg H2O

Question 3

SIMPLE MOLECULAR: What are the atoms in the molecules held together by? And what forces are there between the molecules?

Answer 3

• Atoms in molecules*: Strong forces called covalent bonds
• Molecules*: Very weak forces

Question 4

What are the properties of Simple Molecular substances?

Answer 4

• Low melting and boiling points
• Tend to be soft and/or have little strength
• Do not conduct electricity

Question 5

What sort of elements are simple molecular substances?

Answer 5

Non-metallic elements

Question 6

Giant Covalent Substances: How are the giant structures made?

Answer 6

Strong covalent bonds join atoms together in large numbers to make giant structures

Question 7

Giant Covalent Substances: Give 2 examples

Answer 7

Diamond and graphite

Question 8

Giant Covalent Substances: Strength of bonds?

Answer 8

Very strong

Question 9

Giant Covalent Substances: Properties?

Answer 9

• Very high melting points
• Very hard (except graphite)
• Don’t conduct electricity (except graphite)
  
  • Insoluble in all solvents

Question 10

Giant Metallic Structures: What is the structure of the atoms in metals?

Answer 10

The atoms in metals are in layers which can slide over each other, this makes it possible to bend them or beat them into shape

Question 11

Giant Metallic Structures: Properties?

Answer 11

• Metals are strong
• Metals have high melting points
• Metals are malleable
• Metals are good conductors of electricity and heat
• Metals are listrous (shiny)

ALL BECAUSE THEY HAVE STRONG BONDS

Question 12

Giant Ionic Structures: What are they made up of?

Answer 12

Made up of positive metal ions and negative non-metal ions

Question 13

Giant Ionic Structures: What are they arrange like?

Answer 13

In a regular lattice so that each positive ions is surrounded by a negative ion and vise versa

The particles are held together by the strong attraction of positive for negative

Question 14

Giant Ionic Structures: Properties?

Answer 14

• High melting and boiling points
• Hard but brittle
• Conduct electricity only when melted or dissolved in water
• Many ionic substances are soluble in water

Question 15

What are alloys?

Answer 15

Mixtures of metals

Question 16

Why are alloys made?

Answer 16

Additional elements are added to improve the properties of the metal

Question 17

In terms of atom size, why are alloys stronger than the origional?

Answer 17

In an alloy, the atoms have different sizes this means they can no longer slide so easily. This makes the alloy harder and stronger than the origional material

Question 18

What are nanoparticles?

Answer 18

Smal particles measuring 1-100 nanometers

1nm = 0.000 000 001

Question 19

What are nanotubes?

Answer 19

Fullerenes (molecules of carbon) joined together, hollow carbon tubes

Question 20

Why are nanotubes strong?

Answer 20

Because of the covalent bonds

Question 21

Give some uses of nanotubes in nanoscience

Answer 21

• Can be used to make stronger, lighter building materials
• New cosmetics that don’t leave white marks
• Can be used in tiny electrical circuits for computer chips

Question 22

What determines the properties of plastic?

Answer 22

The bonds between the different molecule chains

Question 23

What affects the properties of polymers?

Answer 23

The starting materials and reaction conditions