Elements, Compounds and Mixtures

Question 1

What is matter?

Answer 1

Anything that has mass and volume, it can be a single chemical substance or a complex mixture of substances

Question 2

What can matter be separated into?

Answer 2

Mixtures (variable composition) and pure substances (constant composition)

Question 3

How can pure substances be converted into mixtures?

Answer 3

Physical methods: preparing mixtures

Question 4

How can mixtures be converted into pure substances?

Answer 4

Physical methods: separating individual components

Question 5

What can mixtures be separated into?

Answer 5

Heterogeneous and homogeneous mixtures

Question 6

What is a heterogeneous mixture?

Answer 6

Multiple phase, variable properties within a sample, non-uniform appearance

Question 7

What is a homogeneous mixture?

Answer 7

Single phase, same properties throughout the mixture, uniform appearance and includes solutions

Question 8

What is the process called when a gas becomes a solid?

Answer 8

Deposition

Question 9

Describe the structure of a solid

Answer 9

Regular arrangement, rigid structure, molecules vibrate in space

Question 10

Describe the structure of a liquid

Answer 10

Assumes the shape of the container, molecules move around one another

Question 11

Describe the structure of a gas

Answer 11

Assumes volume of container, molecules move rapidly in three dimensions

Question 12

What is electrical conductivity?

Answer 12

Ability to transmit electricity

Question 13

What is heat conductivity?

Answer 13

Ability to transfer heat energy

Question 14

What is density?

Answer 14

Mass-to-volume ration

Question 15

What is melting point?

Answer 15

Temperature at which a solid becomes a liquid

Question 16

What is boiling point?

Answer 16

Temperature at which a liquid becomes a gas

Question 17

What is refractive index?

Answer 17

How light passing through a material is bent

Question 18

What is malleability?

Answer 18

Ability to be shaped by hammering

Question 19

What is ductility?

Answer 19

Ability to be shaped by pulling into a wire

Question 20

What are intensive properties?

Answer 20

Do not depend on the amount of matter present and can be used to identify substances

Question 21

What are examples of intensive properties?

Answer 21

Density, colour, boiling point

Question 22

Can intensive or extensive properties be used to identify substances?

Answer 22

Intensive

Question 23

What are extensive properties?

Answer 23

Depends on the amount of matter present

Question 24

What are examples of extensive properties

Answer 24

Mass, volume, weight

Question 25

What are physical properties?

Answer 25

Observed by examining a sample of pure substance and arise from molecular structure and strength of intermolecular interactions

Question 26

What are chemical properties?

Answer 26

Observed in the course of a chemical reaction and arise from the distribution of electrons around the atom's nucleus, particularly the outer (valence) electrons

Question 27

Describe pure substances

Answer 27

- Fixed composition - Properties do not vary - Cannot be separated into simpler substances by physical methods - Can only be changed in identity and appearance by chemical methods

Question 28

What is an element?

Answer 28

A substance which cannot be split up into two or more simple substances by chemical means

Question 29

What are compounds?

Answer 29

A substance that contains two or more elements chemically combined in a fixed proportion

Question 30

What is a molecule?

Answer 30

A group of two or more atoms that are joined together

Question 31

Describe Atomic Theory

Answer 31

- Observation: elements combine in fixed ratios - All matter is composed of atoms - Different elements have different types of atom - Can be characterised by atomic weight - All atoms of the same element are identical - Atoms cannot be made or destroyed - Compounds are composed of two or more atoms chemically combined in fixed proportions - Chemical reactions rearrange the atoms, changing the ratios of chemical combination, thus the identity of the compounds

Question 32

Where is most of the mass of an atom found?

Answer 32

The atom's nucleus (protons and neutrons)

Question 33

What is the mass of an electron?

Answer 33

Negligible

Question 34

What is combining power (valency)?

Answer 34

Ability to form chemical bonds

Question 35

How is the word Chlorine derived?

Answer 35

Greek for yellowish/green

Question 36

How is the word Helium derived?

Answer 36

Greek for sun

Question 37

How is the word Calcium derived?

Answer 37

Latin for lime

Question 38

How is the word Carbon derived?

Answer 38

Latin for charcoal

Question 39

How is the word Iron derived?

Answer 39

Anglo-Saxon, symbol Fe is Latin

Question 40

What is Relative Atomic Mass (RAM)?

Answer 40

The mass of one atom of an element divided by the mass of one twelfth of an atom of Carbon-12

Question 41

How do you calculate Relative Molecular Mass (RMM)?

Answer 41

Calculated by adding the atomic masses of atoms in a molecule (Mass of one molecule of a substance divided by one twelfth times the mass of one atom of Carbon-12)

Question 42

Describe mixtures

Answer 42

- Variable composition - Components retain their identity - Separable into pure substances by physical methods - Mixtures of different compositions may have widely different properties

Question 43

Are colloids homogeneous or heterogeneous?

Answer 43

Visually homogeneous but microscopically heterogeneous

Question 44

How are mixtures separated?

Answer 44

Uses differences in physical properties

Question 45

Describe filtration

Answer 45

Select components by particle size (solid/ liquid)

Question 46

Describe crystallisation

Answer 46

Select components by solubility (solid from solution)

Question 47

Describe extraction

Answer 47

Select components by solubility (solid or liquid from solution)

Question 48

Describe evaporation and distillation

Answer 48

Select components by boiling point (from solution or liquid-liquid)

Question 49

Describe magnetisation

Answer 49

Magnetic metal from other compounds

Question 50

Describe chromotography

Answer 50

Select components by affinity for solid or mobile phases