Groups 0, 7 and 11

Question 1

Why can some elements be classified as being in specific groups due to their position in the periodic table?

Answer 1

Because​ ​they​ ​have​ ​the​ ​same​ ​number​ ​of electrons​ ​in​ ​their​ ​outer​ ​shell​ ​(position​ ​in​ ​the​ ​periodic​ ​table​ ​determines​ ​this), therefore​ ​they​ ​have​ ​the​ ​same​ ​chemical​ ​properties

Question 2

What are groups 1, 7 and 0’s names?

Answer 2

Group 1 is alkali metals, group 7 halogens and group 0 noble gases

Question 3

What are some features of group 1 metals?

Answer 3

-They are soft, this increases going down the group (due to the weakness of their metallic bonds)
-They have relatively low melting points
-They are very chemically reactive

Question 4

What do the reactions of lithium, sodium and potassium with water make?

Answer 4

All these elements are in group 1. They react​ ​vigorously​ ​with​ ​water​ ​to create​ ​an​ ​alkaline​ ​metal​ ​hydroxide​ ​and​ ​hydrogen. e.g. lithium + water –> lithium hydroxide + hydrogen

Question 5

Describe the pattern in reactivity of the alkali metals, lithium, sodium and potassium, with water; and use this pattern to predict the reactivity of other alkali metals

Answer 5

lithium = fizzes​ ​steadily
sodium = melts​ ​into​ ​a​ ​ball​ ​then​ ​fizzes​ ​quickly
potassium = gives​ ​off​ ​sparks​ ​and​ ​hydrogen​ ​burns​ ​with​ ​a​ ​lilac​ ​flame

As the reactions get more vigorous going down group 1 this indicates that reactivity increases going down the group

Question 6

Explain the alkali metals’ pattern in reactivity in terms of electronic configurations

Answer 6

Reactivity increases down group 1 because the size of the atoms is increasing. this means that there is an increased distance of the outer electrons from the nucleus. The negative outer electrons being lost more easily as they have a weaker attraction to the positive nucleus

Question 7

Describe the chemical test for chlorine

Answer 7

The test for chlorine gas is damp blue litmus paper which initially turns red and then bleaches white

Question 8

Recall the colours and physical states of chlorine, bromine and iodine at room temperature

Answer 8

At room temperature:
-Chlorine is a yellow-green gas
-Bromine is a red-brown liquid
- Iodine is a dark-grey or purple solid

Question 9

Knowing the states of chlorine, bromine and iodine what can you predict about the other halogens?

Answer 9

Chlorine, bromine and iodine show a trend in the state going from a gas to a liquid to a solid.
This suggests that halogens higher up the group than chlorine are gases with lower boiling points.
And halogens lower down the group than iodine are solids with higher melting points

Question 10

Describe the reactions of the halogens with metals to form metal halides, and use this pattern to predict the reactions of other halogens

Answer 10

They react with metals to form salts/ionic compounds.

The reaction is less vigorous moving down the group however they still all react to form metal halides.

Question 11

Describe the relative reactivity of halogens as shown by their displacement reactions with halide ions in aqueous solution

Answer 11

A more reactive halogen can displace a less reactive halogen from solutions of its salts. This happens because as you go down the group reactivity decreases.
e.g. chlorine + potassium iodide → potassium chloride + iodine

Question 12

Describe the reactions of the halogens with hydrogen to form hydrogen halides, and use this pattern to predict the reactions of other halogens

Answer 12

The hydrogen halides are gases at room temperature. They dissolve in water to produce acidic solutions.
The reaction becomes less vigorous down the group.

e.g. Hydrogen (g) + chlorine (g) –> Hydrogen chloride (g)
Hydrogen chloride (g) + water (l) –> hydrochloric acid (aq)

Question 13

Explain why these displacement reactions are redox reactions in terms of gain and loss of electrons,
identifying which of these are oxidised and which are reduced

Answer 13

Oxidation is loss and reduction is gain of electrons.
A more reactive halogen displaces the less reactive one and forms a negative ion itself, therefore being reduced as its has gained electrons.
The less reactive halogen which has been displaced is oxidised as it loses the electrons which transfer to the more reactive halogen. It goes from a negative ion to a neutrally charged one.

Reduction and oxidation take place at the same time so these are called redox reactions.

Question 14

Why does reactivity decrease going down group 7?

Answer 14

Because as you go down the group the size of the atoms increase, the outer shell becomes further from the nucleus. Attraction decreases between the positive nucleus towards the negative outer shell electrons, making it more difficult to gain electrons. So the halogen becomes less reactive.

Question 15

Why are halogens reactive?

Answer 15

Halogens have seven outer electrons, which means they have one less electron than a stable noble gas configuration. This makes them highly reactive, as they have a strong tendency to gain one electron and achieve a stable electron configuration.

Question 16

Explain why the noble gases are chemically inert, compared with the other elements, in terms of their electronic configurations

Answer 16

They have full outer shells meaning they are very stable and therefore inert

Question 17

What are some properties of Group 0?

Answer 17

• They are inert.
• They are monatomic because as inert elements they don’t form molecules.
• Low boiling points
• Have low density
• Are non-flammable

Question 18

Explain how the uses of noble gases depend on their inertness, low density and/or non-flammability
(Give examples of uses based on their properties)

Answer 18

●Low​ ​density​ ​=​ ​Helium​ ​used​ ​in​ ​balloons​ ​and​ ​airships​ ​since​ ​it​ ​is​ ​much​ ​less​ ​dense than​ ​air,​ ​so​ ​balloons​ ​filled​ ​with​ ​it​ ​float​ ​upwards
● Inertness​ ​&​ ​non-flammability​ ​=​ ​argon,​ ​krypton​ ​and​ ​xenon​ ​inside​ ​light​ ​bulbs, stops​ ​the​ ​filament​ ​burning​ ​away
● Inertness=​ ​argon​ ​used​ ​as​ ​a​ ​shield​ ​gas​ ​during​ ​welding,​ ​it​ ​is​ ​also​ ​denser​ ​than​ ​air which​ ​keeps​ ​it​ ​away​ ​from​ ​the​ ​metal

Question 19

Describe the pattern in the physical properties of some noble gases

Answer 19

The boiling points and density increase going down the group. This is because of their increasing relative atomic mass

Question 20

Describe the practical for investigating displacement reactions of halogens reacting with halide ions in solution.

Answer 20

Have a spotting tile, with 4 sections containing potassium chloride, another 4 containing potassium bromide and the other 4 containing potassium iodide. Add chlorine water to one of each solution and repeat with bromine water then iodine water. Observe the results.
All tiles of potassium chloride should have no change as no reaction took place because the chloride was more/just as reactive as the halogen solution.
The potassium bromide tile which chlorine was dropped int should be the only one that changes colour to a faint yellow as the chlorine displaced the bromide.
The potassium iodide tile with chlorine in it and the one with bromine it should have each reacted to become brown. This is because bromine and chlorine are more reactive than iodine so displace it.

Question 21

What is the definition of a redox reaction?

Answer 21

A redox reaction is one in which one substance is reduced and the other oxidised. There is no overall gain or loss of electrons.

Question 22

What do ionic equations show?

Answer 22

Ionic equations only show the substance that have been oxidised, reduced or changed state in the reaction.
Ions which aren’t involved are removed and called spectator ions.