Unit 2 - Structures and Properties Flashcards Preview

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Flashcards in Unit 2 - Structures and Properties Deck (24):
1

Name the 4 main structures that substances can have?

Simple Molecular

Giant Ionic

Giant Covalent

Giant Metallic

2

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

Small molecules eg H2O

3

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

Atoms in moleculesStrong forces called covalent bonds

Molecules: Very weak forces

4

What are the properties of Simple Molecular substances?

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

5

What sort of elements are simple molecular substances?

Non-metallic elements

6

Giant Covalent Substances: How are the giant structures made?

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

7

Giant Covalent Substances: Give 2 examples

 

Diamond and graphite

8

Giant Covalent Substances: Strength of bonds?

Very strong

9

Giant Covalent Substances: Properties?

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

10

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

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

11

Giant Metallic Structures: Properties?

  • 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

12

Giant Ionic Structures: What are they made up of?

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

13

Giant Ionic Structures: What are they arrange like?

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

14

Giant Ionic Structures: Properties?

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

15

What are alloys?

Mixtures of metals

16

Why are alloys made?

Additional elements are added to improve the properties of the metal

17

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

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

18

What are nanoparticles?

Smal particles measuring 1-100 nanometers

1nm = 0.000 000 001

19

What are nanotubes?

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

20

Why are nanotubes strong?

Because of the covalent bonds

21

Give some uses of nanotubes in nanoscience

  • 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

22

What determines the properties of plastic?

The bonds between the different molecule chains

23

What affects the properties of polymers?

The starting materials and reaction conditions

24