C3

Question 1

How did Newlands and Mendeleev attempt to classify the elements?

Answer 1

Arranging them in order of their atomic weights

Elements with similar properties are in columns, known as groups

Question 2

Why is it called the periodic table?

Answer 2

Similar properties occur at regular intervals

Question 3

What was wrong with the early periodic tables?

Answer 3

They were incomplete

Some elements were placed in inappropriate groups of the strict order of atomic weights were followed

Question 4

What did Mendeleev do to overcome the problems with that early period tables?

Answer 4

He left gaps for elements he thought hadn’t been discovered

Question 5

How is the modern periodic table arranged? And why?

Answer 5

In order of atomic (proton) numbers

Because electrons, protons and neutrons were discovered in the early 20th century

Question 6

What do elements in the same group all have?

Answer 6

The same number of electrons in the highest occupied energy level

Question 7

What are group 1 of the periodic table known as?

Answer 7

Alkali metals

Question 8

What characteristics do the elements in group 1 have?

Answer 8

Metals with low density

React with non-metals to form ionic compounds in which the metal ion carries a charge of +1. The compounds are white solids that dissolve in water to form colourless solutions.

React with water, releasing hydrogen

Form hydroxides that dissolve in water to give alkaline solutions

Question 9

What happens when you go down Group 1?

Answer 9

The more reactive the element

The lower its melting point and boiling point

Question 10

What characteristics do transition metals have in common, compared to Group 1?

Answer 10

Higher melting points (except Mercury) and higher densities
Stronger and harder
Much less reactive and so do not react vigorously with water or oxygen

Question 11

What else do you know about transition metals?

Answer 11

Many transition elements have ions with different charges
Form coloured compounds
Useful as catalysts

Question 12

What are the elements in Group 7 known as?

Answer 12

The halogens

Question 13

What do Group 7 produce when reacted with metals?

Answer 13

Ionic compounds in which the halide ion carries the charge -1

Question 14

What happens when you go down Group 7?

Answer 14

The less reactive the element

The higher it’s melting point and boiling point

Question 15

What can a more reactive halogen do to a less reactive halogen?

Answer 15

More reactive displaces less reactive from an aqueous solution of its salt

Question 16

How can you explain the trends in reactivity writhing groups?

Answer 16

The higher the energy level of the outer electrons:
The more easily electrons are lost
The less easily electrons are gained

Question 17

How do hard and soft water react with soap?

Which needs more soap to lather?

Answer 17

Hard = reacts with soap to form scum, so more soap is needed to lather
Soft = readily forms lather with soap

Question 18

What does hard water contain and how do these compounds get into the water?

Answer 18

Contains dissolved compounds, usually of calcium or magnesium
Compounds are dissolved when water comes into contact with rocks

Question 19

What are the 2 types of hard water? How can you tell the difference?

Answer 19

Permanent hard water = remains hard when boiled

Temporary hard water = softened by boiling

Question 20

What doesn’t prorate hard water contain, and what happens when it is heated?

Answer 20

Contains hydrocarbonate ions that decompose on heating to produce carbonate ions

Question 21

What do the carbonate ions formed from the hydrocarbonate ions in temporary hard water react with the form precipitates?

Answer 21

Calcium and magnesium

Question 22

Why does hard water increase costs? (Including temporary hard water)

Answer 22

More soap is needed

Temporary hard water produced scale when heated which reduces efficiency of heating systems and kettles

Question 23

What are the benefits of hard water?

Answer 23

Calcium compounds are good for development and maintenance of bones and teeth
Also help to reduce heart disease

Question 24

How do you remove the dissolved calcium and magnesium ions in hard water to make it soft? (Explain the 2 ways)

Answer 24

Add sodium carbonate, reacts with calcium and magnesium ions to form precipitate of calcium carbonate and magnesium carbonate

Use commercial water softeners e.g ion exchange columns containing hydrogen ions or sodium ions
These replace the calcium and magnesium ions when hard water passes through column

Question 25

What does human drinking water need to contain?

Answer 25

Sufficiently low levels of dissolved salts and microbes

Question 26

How is human drinking water produced to the correct quality?

Answer 26

Choose an appropriate source Pass water through filter beds to remove any solids Sterilise with chlorine

Question 27

What do water filters contain?

Answer 27

Carbon, silver and ion exchange resins

Question 28

What does adding chlorine to water do?

Answer 28

Reduce microbes

Question 29

What does adding fluorine to water do?

Answer 29

Improve dental health

Question 30

What are the arguments against adding flouride?

Answer 30

Takes away people's personal choice to take flouride as they're forced to drink it (unethical) Linked to teeth staining, osteoporosis and cancer

Question 31

What are the arguments for adding flouride?

Answer 31

Simple measure to improve public health | Strengthens enamel of teeth which prevents decay, cavities and tooth loss

Question 32

How is pure water produced?

Answer 32

Distillation

Question 33

What is the disadvantage of distillation?

Answer 33

Needs large amounts of energy, so very expensive

Question 34

What is energy measured in?

Answer 34

Joules (J)

Question 35

How can you compare the amount of energy released by fuels and foods?

Answer 35

Measure the amount of energy released when a substance is burned using simple calorimetry

Question 36

How can you calculate the amount of energy released or absorbed by a chemical reaction in solution? What type of reactions can this method be used for?

Answer 36

Measure the temperate change of the solution when the reagents are mixed in an insulated container Reactions of solids with water or neutralisation reactions

Question 37

During a chemical faction when is energy supplied?

Answer 37

To break bonds

Question 38

During a chemical reaction when is energy released?

Answer 38

When bonds are formed

Question 39

In an exothermic reaction, is the energy released from breaking bonds smaller or greater than the energy to break bonds?

Answer 39

Greater than

Question 40

In an endothermic reaction is the energy released from forming bonds smaller or greater than the energy need to break bonds?

Answer 40

Smaller than

Question 41

How can hydrogen be used as a fuel?

Answer 41

Burned as a fuel in combustion engines | Used in fuel cells that produce electricity to power vehicles

Question 42

What does hydrogen and oxygen produce?

Answer 42

Water

Question 43

``` What colours do the flames go in the flame test for: Lithium Sodium Potassium Calcium Barium ```

Answer 43

``` Crimson Yellow Lilac Red Green ```

Question 44

What do aluminium, calcium and magnesium ions form when reacted with sodium hydroxide solution?

Answer 44

White precipitates

Question 45

Which hydroxide precipitate dissolves in excess sodium hydroxide solution?

Answer 45

Aluminium hydroxide precipitate

Question 46

What colour precipitate is formed when sodium hydroxide solution is reacted with: Copper(II) Iron(II) Iron(III)

Answer 46

Blue Green Brown

Question 47

What do carbonates produce when reacted with dilute acids?

Answer 47

Carbon dioxide

Question 48

What does carbon dioxide produce with limewater? | What does the limewater turn?

Answer 48

White precipitate Cloudy

Question 49

How do you test for halide ions?

Answer 49

Add silver nitrate solution in the presence of dilute nitric acid Precipitate is produced

Question 50

What colour precipitate is produced during the halide ion test for: Silver chloride Silver bromide Silver iodide

Answer 50

White Cream Yellow

Question 51

How do you test for surface ions?

Answer 51

Add barium chloride solution in the presence of dilute hydrochloric acid White precipitate produced

Question 52

How can the volumes of acid and alkali that react with each other be measured?

Answer 52

Titration using a suitable indicator

Question 53

If the concentration of one of the reactants is known, how can the results of a titration be used?

Answer 53

To find the concentration of the other reactant

Question 54

What are the raw materials needed for the Haber process? Where are these obtained from?

Answer 54

Nitrogen and hydrogen Nitrogen from air Hydrogen from natural gas or other sources

Question 55

What happens in the Haber process? What is produced?

Answer 55

Purified gasses Passed over a catalyst At a high temperature (about 450 degrees) At a high pressure (about 200 atmospheres) Some of hydrogen and nitrogen reacts to form ammonia Ammonia liquefies when cooled and is then removed

Question 56

What type of reaction produces ammonia?

Answer 56

Reversible

Question 57

What happens to the remaining hydrogen and nitrogen?

Answer 57

Recycled

Question 58

If a reaction occurs in a closed system, when is equilibrium reached?

Answer 58

When the reactions occur at exactly the same rate in each direction

Question 59

What happens to the yield of exothermic and endothermic reactions when the temperature increases?

Answer 59

Yield increases from exothermic | Yield decreases from endothermic