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Chemistry Unit 3 > C3 > Flashcards

C3 Flashcards

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1
Q

How did Newlands and Mendeleev attempt to classify the elements?

A

Arranging them in order of their atomic weights

Elements with similar properties are in columns, known as groups

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2
Q

Why is it called the periodic table?

A

Similar properties occur at regular intervals

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3
Q

What was wrong with the early periodic tables?

A

They were incomplete

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

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4
Q

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

A

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

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5
Q

How is the modern periodic table arranged? And why?

A

In order of atomic (proton) numbers

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

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6
Q

What do elements in the same group all have?

A

The same number of electrons in the highest occupied energy level

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7
Q

What are group 1 of the periodic table known as?

A

Alkali metals

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8
Q

What characteristics do the elements in group 1 have?

A

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

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9
Q

What happens when you go down Group 1?

A

The more reactive the element

The lower its melting point and boiling point

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10
Q

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

A

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

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11
Q

What else do you know about transition metals?

A

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

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12
Q

What are the elements in Group 7 known as?

A

The halogens

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13
Q

What do Group 7 produce when reacted with metals?

A

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

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14
Q

What happens when you go down Group 7?

A

The less reactive the element

The higher it’s melting point and boiling point

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15
Q

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

A

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

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16
Q

How can you explain the trends in reactivity writhing groups?

A

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

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17
Q

How do hard and soft water react with soap?

Which needs more soap to lather?

A 
Hard = reacts with soap to form scum, so more soap is needed to lather
Soft = readily forms lather with soap
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18
Q

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

A

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

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19
Q

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

A

Permanent hard water = remains hard when boiled

Temporary hard water = softened by boiling

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20
Q

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

A

Contains hydrocarbonate ions that decompose on heating to produce carbonate ions

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21
Q

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

A

Calcium and magnesium

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22
Q

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

A

More soap is needed

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

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23
Q

What are the benefits of hard water?

A

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

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24
Q

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

A

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

25
Q

What does human drinking water need to contain?

A

Sufficiently low levels of dissolved salts and microbes

26
Q

How is human drinking water produced to the correct quality?

A

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

27
Q

What do water filters contain?

A

Carbon, silver and ion exchange resins

28
Q

What does adding chlorine to water do?

A

Reduce microbes

29
Q

What does adding fluorine to water do?

A

Improve dental health

30
Q

What are the arguments against adding flouride?

A

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

31
Q

What are the arguments for adding flouride?

A

Simple measure to improve public health

Strengthens enamel of teeth which prevents decay, cavities and tooth loss

32
Q

How is pure water produced?

A

Distillation

33
Q

What is the disadvantage of distillation?

A

Needs large amounts of energy, so very expensive

34
Q

What is energy measured in?

A

Joules (J)

35
Q

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

A

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

36
Q

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?

A

Measure the temperate change of the solution when the reagents are mixed in an insulated container

Reactions of solids with water or neutralisation reactions

37
Q

During a chemical faction when is energy supplied?

A

To break bonds

38
Q

During a chemical reaction when is energy released?

A

When bonds are formed

39
Q

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

A

Greater than

40
Q

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

A

Smaller than

41
Q

How can hydrogen be used as a fuel?

A

Burned as a fuel in combustion engines

Used in fuel cells that produce electricity to power vehicles

42
Q

What does hydrogen and oxygen produce?

A

Water

43
Q 
What colours do the flames go in the flame test for:
Lithium 
Sodium
Potassium
Calcium
Barium
A 
Crimson 
Yellow
Lilac
Red
Green
44
Q

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

A

White precipitates

45
Q

Which hydroxide precipitate dissolves in excess sodium hydroxide solution?

A

Aluminium hydroxide precipitate

46
Q

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

A

Blue
Green
Brown

47
Q

What do carbonates produce when reacted with dilute acids?

A

Carbon dioxide

48
Q

What does carbon dioxide produce with limewater?

What does the limewater turn?

A

White precipitate

Cloudy

49
Q

How do you test for halide ions?

A

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

50
Q

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

A

White
Cream
Yellow

51
Q

How do you test for surface ions?

A

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

52
Q

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

A

Titration using a suitable indicator

53
Q

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

A

To find the concentration of the other reactant

54
Q

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

A

Nitrogen and hydrogen

Nitrogen from air

Hydrogen from natural gas or other sources

55
Q

What happens in the Haber process? What is produced?

A

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

56
Q

What type of reaction produces ammonia?

A

Reversible

57
Q

What happens to the remaining hydrogen and nitrogen?

A

Recycled

58
Q

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

A

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

59
Q

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

A

Yield increases from exothermic

Yield decreases from endothermic

Chemistry Unit 3 (1 decks)

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