Elements, Water And Organic Chemistry Flashcards

1
Q

What used to be the two ways to categorise elements?

A

Their physical and chemical properties or their relative atomic mass.

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2
Q

What is the Newlands Law of Octaves?

A

He noticed that every eighth element had similar properties and so he listed some of the known elements in rows of sevens.

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3
Q

How many rows of seven were there for Newlands Law of Octaves?

A

Eight.

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4
Q

Which row did Newlands Law of Octaves break down on?

A

Third row with transition metals like titanium and iron.

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5
Q

Why was Newlands work criticised?

A

Contained elements that didn’t have similar properties eg carbon and titanium.
He mixed up metals and non metals eg oxygen and iron.
He didn’t leave any gaps for elements that hadn’t been discovered yet.

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6
Q

How did Dmitri Mendeleev put the elements in order?

A

Atomic mass but he found he had to leave gaps in order to keep elements with similar properties in the same vertical columns (groups).

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7
Q

Why was Dmitri Mendeleev leaving gaps really clever?

A

Predicted the properties of so far undiscovered elements.

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8
Q

What is the modern periodic table based on?

A

Electronic structure.

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9
Q

What can you predict using electron arrangement of elements?

A

The element’s chemical properties.

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10
Q

What are electrons in an atom set out in?

A

Shells which correspond to an energy level.

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11
Q

What do elements in the same group have?

A

The same number of electrons in their highest occupied energy level (outer shell).

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12
Q

What is the group number of an element equal to?

A

The number of electrons in the highest occupied energy level.

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13
Q

What charge attracts electrons and holds them in place?

A

Positive charge from the nucleus.

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14
Q

What happens to the attraction when the nucleus is further away from the electrons?

A

It decreases as the electron is shielded by more electron shells.

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15
Q

Why do Group 1 metals get more reactive as you go down the group?

A

The atoms of each element get larger so the outer shell electron gets further away from the nucleus and is shielded by more electron shells. The further an electron is from the positive nucleus, the easier it can be lost in reactions.

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16
Q

What effect does increased distance and shielding have on the reactivity of an element?

A

It is less likely to gain an electron as there is less attraction from the nucleus pulling electrons into the atom.

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17
Q

What happens as you go down Group 1?

A

They become more reactive, have lower melting and boiling points.

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18
Q

Do the alkali metals have low or high density?

A

Low.

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19
Q

Name the alkali metals.

A

Lithium, Sodium, Potassium, Rubidium and Caesium.

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20
Q

How many outer electrons does Group 1 have?

A

1 which makes them very reactive and gives them all similar properties.

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21
Q

What compounds do alkali metals form with non metals?

A

Ionic, they lose their outer electron to become 1+ ion. They hate the electron so won’t share (no covalent bonding).

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22
Q

What else do alkali metals make with non metals?

A

White compounds that dissolve in water to form colourless solutions.

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23
Q

What gas do alkali metals make with water?

A

Hydrogen gas.

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24
Q

Which alkali metals react vigorously with water?

A

Lithium, sodium or potassium.

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25
Q

What happens when you put lithium, sodium or potassium in water?

A

They float and move about the surface, fizzing furiously.

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26
Q

Which alkali metal is ignited in water?

A

Potassium.

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27
Q

How can you indicate hydrogen?

A

A lighted splint which will make a squeaky pop as the H2 ignites.

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28
Q

What do alkali metals with water and hydrogen form?

A

Hydroxides that dissolve in water to give alkaline solutions.

29
Q

Give an equation of an alkali and water.

A

2NA(s) + 2H2O(I) = 2NAOh (aq) + H2 (g)

30
Q

What happens as you go down Group 7?

A

They become less reactive because it’s harder to gain an extra electron because the outer shell is further from the nucleus.

31
Q

What are the coloured vapours of the halogens?

A

Fluorine, poisonous yellow gas
Chlorine, poisonous dense green gas
Bromine, dense poisonous red brown volatile liquid
Iodine, dark grey crystalline solid/purple vapour

32
Q

What do halogens form ionic bonds with?

A

Metals, they form 1- ions called HALIDES.

33
Q

How do you test for halide ions?

A

Add dilute nitric acid followed by silver nitrate solution.

34
Q

What precipitate does chloride give when added to dilute nitric acid then silver nitrate solution?

A

White of silver chloride.

35
Q

What precipitate does bromide give when added to dilute nitric acid followed by silver nitrate solution?

A

Cream of silver bromide.

36
Q

What precipitate does iodide give when added to dilute nitric acid and silver nitrate solution?

A

Yellow of silver iodide.

37
Q

What will more reactive halogens displace?

A

Less reactive ones from an aqueous solution of its salt.

38
Q

Give an example of a more reactive halogen displacing a less reactive one?

A

Chlorine can displace bromine and iodine. Bromine will also displace iodine because of the trend in reactivity.

39
Q

Give an equation of a displacement of halogens.

A

Cl2 (g) + 2KI(aq) = I2 (aq) + 2KCL (aq)

40
Q

What are the properties of the transitional metals?

A

Good conductors of heat and electricity, they are very dense, strong, shiny, they are much less reactive than Group 1, much denser, stronger, harder than Group 1 and have much higher melting points (except for Mercury which is liquid at room temp)

41
Q

How many ions do transitional metals often have?

A

Two or three eg copper Cu+, Cu2+

42
Q

What do the different ions of a transitional metal do?

A

Usually form different coloured compounds eg

Fe2+ give green and Fe3+ usually form red/brown (rust)

43
Q

Why are the compounds of transitional metals colourful?

A

Due to the ion they contain, eg copper(III) sulfate is blue. The colours in gemstones like green emeralds and pottery glazes also. Weathered copper is a lovely colourful green.

44
Q

How did John Dalton organise elements?

A

In order of their masses, measured in various chemical reactions.

44
Q

Why was Newlands law of octaves criticised?

A

Assumed all elements had been discovered, despite chemists still finding new ones and filled in his octaves meaning some of the elements were not similar at all.

45
Q

Which two atoms didn’t fit with Mendeleev’s pattern of putting elements in order of atomic mass giving vertical groups of similar elements?

A

Argon (noble gas) and potassium (extremely reactive metal). If put in order of atomic mass, argon would be extremely reactive metals such as sodium whilst potassium would be put with noble gases. Argon must be before potassium even though it’s atoms are heavier.

46
Q

What do plants need in order to grow?

A

Nitrogen, even though nitrogen gas makes up 80% of gases in the air plants cannot use it directly.

47
Q

How do plants get nitrogen?

A

Soluable nitrates in the soil.

48
Q

What is the problem of harvesting crops in terms of nitrogen?

A

The nitrogen in plants is lost, because the plants do not die and decompose to replace the nitrogen in the soil.

49
Q

How do farmers add nitrogen for the following years crops?

A

Adding nitrate fertilisers to the soil.

50
Q

Who invented the Haber process?

A

Fritz Haber.

51
Q

What are the two raw materials in the Haber process?

A

Nitrogen from the air, hydrogen from natural gas (containing methane CH4)

52
Q

What happens to the nitrogen and hydrogen in the Haber process?

A

Purified and passed over an iron catalyst at high temperatures.

53
Q

What temperature is the hydrogen and nitrogen passed over an iron catalyst at?

A

450 degrees.

54
Q

What pressure is nitrogen and hydrogen passed over an iron catalyst at?

A

200 atmospheres.

55
Q

How can you remove ammonia in the Haber process?

A

Cooling the gases so ammonia liquefies. Can then be separated as nitrogen and hydrogen are still gases.

56
Q

What is the equation of the Haber process?

A

N2 + 3H2 >< 2NH3

57
Q

What happens to the unreacted nitrogen and hydrogen in the Haber process?

A

Recycled back into reaction mixture.

58
Q

What are the two methods used to soften water?

A

Adding sodium carbonate or using an ion exchange column.

59
Q

What happens when you add sodium carbonate to hard water?

A

A reaction takes place where the soluable carbonate ions precipitate out calcium and magnesium ions and the dissolved metal compounds form insoluable carbonates.

60
Q

What is the equation for adding sodium carbonate to water?

A

Ca2+ (aq) + CO3 2- (aq)- CaC03 (s)

61
Q

How does an ion exchange column work?

A

Column contains a resin packed with sodium ions.
Hard water passes through the column.
Sodium ions from the resin are exchanged for the magnesium and calcium ions.

62
Q

What do some ion exchange columnns use as an alternative to sodium ions?

A

Hydrogen ions.

63
Q

True or false, the resin can be recharged with sodium ions after being exchanged for calcium and magnesium ions.

A

True, the resin is washed with salt (sodium chloride) solution which puts the sodium ions back in.

64
Q

How is temporary hardness of water removed?

A

By boiling it.

65
Q

Which calcium and magnesium ions cannot be removed by heating the water?

A

Ions from some salts such as sulphates.

66
Q

What is the reaction that makes scale?

A

When you boil hard water containing hydrogen carbonates, they decompose.
The carbonate ions react with calcium/magnesium ions in the the hard water making precipitates.

67
Q

Why is soft water important in many industrial processes?

A

Hard water can produce scale in boilers, making them more expensive to run.
Can interfere with chemical processes such as dyeing.