Pure substances and mixtures

Question 1

The particle theory:

Answer 1

All matter consists of atoms which are constantly moving.

Question 2

Solid properties: 
Volume: 
Shape:
Particle position:
Particle movement: 
Compressibility:
Attractive forces:

Answer 2

• Has definite volume
• Has definite shape
• Particles are closely packed
• Negligible compressibility
• Quite strong attractive forces
• Particle vibrate in position, bidirectional movement

Question 3

Liquid properties: 
Volume:
Shape:
Particle position:
Particle movement: 
Compressibility:
Attractive forces:

Answer 3

• Has definite volume
• Takes volume and shape of the container
• Particles are less closely packed compared to solids
• Particles move in random motion/ vibrations and translations
• Negligible compressibility
• Moderately strong attractive forces

Question 4

Gas properties:
Volume:
Shape:
Particle position:
Particle movement: 
Compressibility:
Attractive forces:

Answer 4

• Takes volume and shape of the container
• Particles are widely spread apart
• Particle move in rapid random translations
• Particle move rapidly indicating high energy levels
• Easily compressed
• Negligible attractive forces

Question 5

Gas —–> Liquid

Answer 5

condensation

Question 6

Liquid—-> Gas

Answer 6

evaporation

Question 7

Solid—-> Liquid

Answer 7

melting

Question 8

Liquid —-> Solid

Answer 8

freezing

Question 9

Solid—-> Gas

Answer 9

sublimation

Question 10

Gas—–> Solid

Answer 10

deposition

Question 11

Matter:

Answer 11

anything that takes up place and have mass

Question 12

Elements:

Answer 12

• Simplest substance which cannot be decomposed by ordinary physical or chemical emans
• Made up of same type of atoms

Question 13

Compound:

Answer 13

• Pure substance consisting of two or more different elemnts chemically combined in a fixed ration
• Can be decomposed using chemical means

Question 14

Diatomic molecules:

Answer 14

Consist of two atoms of the same elements

e.g. O2, N2

Question 15

Molecules:

Answer 15

• Particles that can exist and move independently of each other

Question 16

Elements can be classed as:

Answer 16

Metals, semi- metals and non- metals

Question 17

Elements can be described according to:

Answer 17

• Lustre
• Electrical conductivity
• Ductility
• Malleability
• MP: melting point
• BP: boiling point

Question 18

Properties of metals: 
Lustre: 
Electrical conductivity: 
Malleabiltiy: 
Ductility: 
MP/ BP:

Answer 18

Lustre: high 
Electrical conductivity: high
Malleabiltiy: high
Ductility: high
MP/ BP: high

Question 19

Properties of semi- metals:
Lustre: 
Electrical conductivity: 
Malleabiltiy: 
Ductility: 
MP/ BP:

Answer 19

Lustre: moderate 
Electrical conductivity: semi- conductor 
Malleabiltiy: moderate
Ductility: moderate 
MP/ BP: high- medium

Question 20

Properties of non- metals: 
Lustre: 
Electrical conductivity: 
Malleabiltiy: 
Ductility: 
MP/ BP:

Answer 20

Lustre: low
Electrical conductivity: low
Malleabiltiy: low/ brittle 
Ductility: none
MP/ BP: low

Question 21

Monoatomic elements:

Answer 21

Found uncombined in nature because they are inert (stable)

Question 22

Mixtures:

Answer 22

Physical combiantions of two or more susbatnces in variable proportion

Question 23

Homogenous mixture:

Answer 23

• A substance with a uniform composition throughout
• The component are indistinguishable
  e. g. salt water, milk, cordial

Question 24

Heterogeneous mixture:

Answer 24

• A substance with non- uniform composition
• Individual components distinguishable
  e. g. sand + water, soil

Question 25

Pure substance properties:

Answer 25

- Cannot be separated into two or more substances by physical means - Always homogenous - Has a fixed chemical structure - Has definite physical properties that do not change

Question 26

Mixture properties:

Answer 26

- Can be physically separated into its components - Homogenous or heterogeneous - Has a variable composition - Physical properties depend on the ratio and properties of the components