Section 2: Chemistry of the elements Flashcards

1
Q

What is a group in the Periodic table?

A

A column

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2
Q

What is a period in the Periodic table?

A

A row

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3
Q

Where are the metals and non-metals in the Periodic table?

A

Metals on the left, transition metals in the middle, non-metals to the right of staircase under boron.

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4
Q

How is a substance classified as a metal?

A

They conduct electricity and heat, and form alkaline metal oxides.

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5
Q

How is a substance classified as a non-metal?

A

They do not conduct, and form acidic non-metal oxides.

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6
Q

Why do elements in the same group have similar chemical properties?

A

Elements in the same group have the same number of electrons in their outer shells. This means they will behave in a similar way, and will react and bond similarly.

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7
Q

What are the noble gases?

A

They are a family of inert gases.

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8
Q

Why are the noble gases inert?

A

They are stable because they have a full outer shell, so they do not need to lose or gain electrons.

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9
Q

Describe the reactions of the group 1 elements with water.

A

They all react to produce a metal hydroxide and hydrogen.
Lithium - fizzing
Sodium - floats, makes small ball, melts, lots of fizzing
Potassium - produces lilac flame, spits around

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10
Q

Describe and explain the relative reactivities of the elements in Group 1.

A

The reactivity increases as you go down the group because there is more distance between the electron and the nucleus, making it easier for the electron to be lost.

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11
Q

What is the colour and physical state of chlorine?

A

green, gas

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12
Q

What is the colour and physical state of bromine?

A

brown, liquid

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13
Q

What is the colour and physical state of iodine?

A

grey, purple vapour, solid

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14
Q

What is the difference between hydrogen chloride and hydrochloric acid?

A

Hydrogen chloride is a gas, hydrochloric acid is the substance formed when hydrogen chloride is dissolved in water.

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15
Q

Why is hydrogen chloride acidic in water but not in methylbenzene?

A

An acid is a substance which dissociates hydrogen ions when dissolved in water. This happens in water, but not in methylbenzene, because methylbenzene is not a polar molecule.

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16
Q

Describe the relative reactivities of the elements in Group 7.

A

The reactivity goes down as you go down the group.

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17
Q

Describe experiments to demonstrate that a more reactive halogen will displace a less reactive halogen from a solution of one of its salts.

A

Using chlorine and potassium bromide:
If you add chlorine to potassium bromide solution, the solution will turn orange as bromine is formed. The more reactive chlorine has displaced the less reactive bromine from potassium bromide.

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18
Q

What happens in terms of reduction and oxidation in a displacement reaction?

A

A displacement reaction is a redox reaction. In the reaction between chlorine and potassium bromide, the potassium ions are spectator ions, and the bromide ions lose electrons, which are gained by the chlorine atoms.

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19
Q

What gases are present in air, and what is their approximate percentage by volume?

A

Nitrogen - 78%
Oxygen - 21%
Argon - 0.9%
Carbon dioxide - 0.04%

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20
Q

Explain how experiments involving the reactions of elements such as copper, iron and phosphorous with air can be used to investigate the percentage by volume of oxygen in air.

A

Copper, iron and phosphorus all react with air. If you know the volume of air that you have, then react it with on of these, then measure the volume of air afterwards; what has been lost is all oxygen that reacted.

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21
Q

How do you make oxygen in a lab?

A

The catalytic decomposition of hydrogen peroxide using manganese oxide as the catalyst.
2H2O2 (aq) –> 2H2O (l) + O2 (g)

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22
Q

How is carbon dioxide made by the thermal decomposition of metal carbonates?

A

When metal carbonates are heated they become carbon dioxide and a metal.
e.g. copper carbonate –> copper oxide + carbon dioxide
CuCO3 –> CuO + CO2

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23
Q

What is the solubility of carbon dioxide?

A

It dissolves in water under pressure.

24
Q

What is the density of carbon dioxide?

A

It is denser than air.

25
Q

Why is carbon dioxide used in fizzy drinks?

A

It dissolves in water under pressure. When you open the bottle, the pressure falls, and the gas bubbles out of solution.

26
Q

Why is carbon dioxide used in fire extinguishers?

A

The dense gas sinks onto the flames and prevents any more oxygen from reaching them.

27
Q

What is the issue with carbon dioxide gas?

A

It is a greenhouse gas, and may contribute to climate change.

28
Q

What is the general reaction of an acid with metals like magnesium, aluminium, zinc and iron?

A

acid + metal –> salt + hydrogen

29
Q

Describe the combustion of hydrogen.

A

2H2 + O2 –> 2H2O

A lot of energy is also formed.

30
Q

What is the chemical test for water?

A

Anhydrous copper sulfate is white, but when you add water, it is rehydrated and turns blue.

31
Q

What is the physical test for water?

A

Cool the water down to 0 degrees C. If the water is pure, then the water should turn to ice.

32
Q

What is the reactivity series?

A

A series of metals that have been arranged in order of the reactivity of the metals and their compounds

33
Q

List the reactivity series.

A

potassium, sodium, lithium, calcium, magnesium, aluminium, (carbon), zinc, iron, (hydrogen), copper, silver, gold

34
Q

How can reactions with water and dilute acids be used to deduce the position of a metal?

A

potassium, sodium, lithium and calcium all react with water and acids
magnesium, zinc and iron all react with acids (and very slowly with water.)
copper doesn’t react with either.

The more vigorous the reaction the more reactive the metal. The more things a metal will react with, the more reactive the metal.

35
Q

Deduce the position of a metal within the reactivity series using displacement reactions between metals and their oxides, and between metals and their salts in aqueous solutions.

A

A metal oxide or a metal salt dissolved in water:
introduce a more reactive metal and it will displace the current one
introduce a less reactive metal and no displacement will take place
From this you can deduce which metals are more and less reactive.

36
Q

What is oxidation?

A

The additional of oxygen

37
Q

What is reduction?

A

The removal of reduction

38
Q

What does redox mean?

A

A redox reaction is one where both reduction and oxidation are happening.

39
Q

What is an oxidising agent?

A

A substance which oxidises something else.

40
Q

What is a reducing agent?

A

A substance which reduces something else.

41
Q

What conditions are required for iron to rust?

A

Presence of oxygen and water. It is accelerated by the presence of an electrolyte.

42
Q

How is rusting prevented by grease, oil, paint or plastic?

A

The grease/oil/paint/plastic acts as a barrier, preventing oxygen and water getting to the iron.

43
Q

How is rusting prevented by galvanising?

A

Galvanised iron is iron that is coated with a layer of zinc. Once the zinc is scratched, the iron still does not rust, because zinc irons and electrons have been formed in the reaction of zinc and oxygen. Any iron atom which has lost electrons to form an ion immediately regains them. If the iron cannot form ions, then it cannot rust.

44
Q

What is the sacrificial protection of iron?

A

Sacrificial is covering a metal with a more reactive metal. What this means is water and/or air will react with the more reactive metal instead of the one underneath.

45
Q

What colours do the flame tests turn for lithium, sodium, potassium and calcium?

A

Lithium - red
Sodium - orange
Potassium - lilac
Calcium - brick red

46
Q

How do you test for ammonium ions using sodium hydroxide solution and identifying the ammonia evolved?

A

Sodium hydroxide solution reacts with ammonium salts to produce ammonia gas. You can smell the gas, or put damp red litmus paper into the gas. It will turn blu, because ammonia is alkaline.

47
Q

What colours are the precipitates for copper, iron (II) and iron (III) when reacted with sodium hydroxide solution?

A

Copper - blue
Iron (II) - green
Iron (III) - orange-brown

48
Q

What colours are the precipitates for chlorine, bromine and iodine when reacted with dilute nitric acid and silver nitrate solution?

A

Chlorine - white
Bromine - cream
Iodine - yellow

49
Q

How do you test for sulphate ions using dilute hydrochloric acid and barium chloride solution?

A

Make a solution of supposed sulphate in pure water, add hydrochloric acid to make it acidic. Add barium chloride solution. A sulphate will produce a white precipitate of barium sulphate.

50
Q

How do you test for carbonate ions using dilute hydrochloric acid and identifying the carbon dioxide evolved?

A

React the carbonate with dilute hydrochloric acid. Bubbles of gas should be produced. Collect the gas, and bubble it into limewater. If it turns cloudy, then it was a carbonate ion.

51
Q

What is the test for hydrogen?

A

When a lit splint is held to hydrogen, a squeaky pop can be heard.

52
Q

What is the test for oxygen?

A

Oxygen will relight a glowing splint.

53
Q

What is the test for carbon dioxide?

A

Bubble carbon dioxide into limewater. The limewater should turn cloudy.

54
Q

What is the test for ammonia?

A

It turns damp red litmus paper blue.

55
Q

What is the test for chlorine?

A

It bleaches damp litmus paper.