5.1.1 - A Simple Model Of The Atom, Symbols, Relative Atomic Mass, Electronic Charge And Isotopes

Question 1

What are all substances made of

Answer 1

Atoms

Question 2

What is an atom

Answer 2

The smallest part of an element that can exist

Question 3

What are atoms of each element represented by

Answer 3

A chemical symbol (eg = Na or O)

Question 4

How are compounds formed

Answer 4

From elements by chemical reactions

Question 5

What do chemical reactions always involve

Answer 5

• The formation of one or more new substances
• a detectable energy change

Question 6

What do compounds contain

Answer 6

Two or more elements chemically combined in fixed proportions

Question 7

How are compounds represented

Answer 7

By formulae using the symbols of the atoms from which they were formed

Question 8

What’s the only way compounds can be separated into elements

Answer 8

By chemical reactions

Question 9

What does a micture consist of

Answer 9

Two or more elements/compounds not chemically combined together

Question 10

What are the chemical proportions of each substance in a mixture like

Answer 10

Unchanged

Question 11

How can mixtures be separated + examples

Answer 11

By physical processes
Eg = filtration, crystallisation, simple distillation, fractional distillation and chromotography

Question 12

What do the physical processes for mixtures being separated not involve

Answer 12

Chemical reactions
No new substances are made

Question 13

What does filtration separate

Answer 13

An insoluble solid from a liquid

Question 14

What is filtration useful for separating

Answer 14

Separating sand from a mixture of sand and water OR an excess reactant from a reaction mixture

Question 15

Why does filtration work

Answer 15

The filter paper has tiny holes/pores in it - they’re large enough to let small molecules + dissolved ions through but not larger particles of the un dissolved solid

Question 16

Steps to filtration

Answer 16

1) one beaker has a micture of solid and liquid, the other has a funnel with filter paper in it
2) the solid and liquid mixtures poured into the filter funnel
3) the liquid drips through the filter paper but the solid particles are caught in the filter paper

Question 17

What is crystallisation used for

Answer 17

To produce solid crystals from a solution

Question 18

How does crystallisation work

Answer 18

When the solutions warmed, so,e of the solvent evaporates leaving crystals behind

Question 19

Example of when crystallisation is used

Answer 19

To obtain copper Sulfate crystals from copper Sulfate solution

Question 20

Steps to crystallisation

Answer 20

1) a solutions placed in an evaporating basin and heated with a Bunsen burner
2) the volume of the solution has decarsed because some waters evaporated - solid particles begin to form in the basin
3) all the water evaporates and leaves solid crystals behind

Question 21

What’s simple distillation used for

Answer 21

To separate a solvent from a solution

Question 22

What’s simple distillation useful for

Answer 22

For producing pure water from seawater

Question 23

How does simple distillation work

Answer 23

• The dissolved solute has a much higher boiling point than the solvent
• when the solutions heated, solvent vapour leaves the solution
• it moves away and is cooled/condensed
• the remaining solution becomes more concentrated as the amount of solvent in it decreases

Question 24

Steps to simple distillation

Answer 24

1) salty waters heated
2) the water vapour cools in the condenser and drips into a beaker
3)the waters condensed and is now in the beaker, the salt stays behind

Question 25

What’s fractional distillation used to separate

Answer 25

To separate different liquids from a mixture of liquids

Question 26

What’s fractional distillation useful for separating

Answer 26

Ethanol from a mixture of ethanol and water AND separating different fractions from crude oil

Question 27

Why does fractional distillation work

Answer 27

Because the different liquids have different boiling points

Question 28

How does fractional distillation work

Answer 28

When the mixtures heated -
1) vapour rises through a column which is hot at the bottom and cooler at the top
2) vapours condense when they reach the part of the column that’s below the temperature of their boiling point
3) each liquids led away from the column

Question 29

What are the two ways to obtaining different liquids from the column

Answer 29

1) by collected different liquids from different parts of the column - the substance with the lowest boiling points collected at the top of the column
2) by continuing to heat the mixture to increase the temperatures in the column - the substance with the lowest boiling points collected first

Question 30

Steps to fractional distillation

Answer 30

1) water and ethanol solution is heated
2) the ethanols evaporates first, cools and then condenses
3) the water left evaporates cools and then condenses

Question 31

What does Papier chromatography separate

Answer 31

Mixtures of soluble substances - often coloured substances (eg = food colourings, inks, dyes or plant pigments)

Question 32

What are the two phases in chromatography

Answer 32

• stationary phase = paper
• mobile phase = the solvent

Question 33

What does a pure substance produce in chromatography

Answer 33

One spot

Question 34

What does an impure substance produce in chromatography

Answer 34

Two or more spots

Question 35

How do you know if two substances are likely the same in chromatography

Answer 35

• if they produce the same number of spots and they’re the same colour
• if the spots travel the same distance up the paper