Group 0: the noble gases

Which gas made up the greatest proportion of the Earth’s early atmosphere?

Figure 4 shows the composition by volume of the Earth’s atmosphere today.

Give the name of the gas in Earth’s atmosphere today that makes up the largest proportion.

Using the information in Figure 4, calculate the percentage of argon and other gases in the Earth’s atmosphere today.

The percentage of oxygen in air can be measured using the apparatus shown in Figure 5.

The oxygen in the air reacts with the heated zinc.

Explain one change that would be seen during the reaction.

Name the product formed when the zinc reacts with oxygen in this experiment.

Figure 6 shows the electron configuration of an argon atom.

State why argon is unreactive.

Argon makes up 0.93% of the Earth’s atmosphere today.

Calculate the volume of argon, in cm³, in 4000 cm³ of air.

This question is about the noble gas xenon.

Xenon is unreactive.

Explain, in terms of its electronic configuration, why xenon is unreactive.

Under extreme conditions, xenon can be made to react with fluorine to form xenon tetrafluoride, XeF₄.

Write the balanced equation for this reaction.

Some information about xenon tetrafluoride is shown in Figure 3.

State and explain, with reasons, the type of structure and bonding in xenon tetrafluoride.

Under extreme conditions, xenon reacts with fluorine to form xenon hexafluoride.

The reaction is exothermic. The energy change for the reaction is –400 kJ mol^–1.

On Figure 4

• add a label to the y‑axis

• draw the reaction profile for this reaction

• label the energy change and the activation energy for the reaction.

This question is about the atmosphere.

Describe the test to show that a gas is oxygen.

Copper reacts with oxygen to form copper oxide.

2.100 g of copper will react completely with 0.529 g of oxygen.

In an experiment, 4.200 g of copper is heated with 50.000 g of oxygen until the reaction is complete.

Calculate the mass of oxygen remaining at the end of the experiment.

mass of oxygen =_........ g

Helium, neon and argon are all inert.

Explain, in terms of electrons, why these gases are inert.

Two pieces of steel can be joined by heating the metal pieces with a very hot flame.

This process is often carried out in an argon atmosphere rather than in air.

Which property makes argon gas suitable for this use?

*(d) Figure 10 shows how plant life and the atmosphere of Earth have changed over time.

Explain the effect that plant life has had on the Earth’s atmosphere and the temperature of the Earth.

You should refer to the information in Figure 10 including

• the plant life

• the amounts of carbon dioxide

• the amounts of oxygen

This question is about the atmosphere.

Describe the test to show that a gas is oxygen.

Copper reacts with oxygen to form copper oxide.

2.100 g of copper will react completely with 0.529 g of oxygen.

In an experiment, 4.200 g of copper is heated with 50.000 g of oxygen until the reaction is complete.

Calculate the mass of oxygen remaining at the end of the experiment.

mass of oxygen =_........ g

Helium, neon and argon are all inert.

Explain, in terms of electrons, why these gases are inert.

Two pieces of steel can be joined by heating the metal pieces with a very hot flame.

This process is often carried out in an argon atmosphere rather than in air.

Which property makes argon gas suitable for this use?

Carbon dioxide is removed from the atmosphere by plants and stored in plants and soil as carbon compounds.

Figure 3 shows the relative amounts of carbon stored in plants and soils in different environments.

relative amount of carbon stored per unit area

Figure 3

It has been suggested that preserving coastal ecosystems is more effective than reforestation in the mitigation of climate change.

Describe how the data in Figure 3 supports this suggestion.

This question is about gases.

When sodium is added to water, hydrogen gas is produced.

Which observation shows that a gas has been produced?

Some damp litmus paper is placed in a gas. The litmus paper is bleached.

Which gas bleaches damp litmus paper?

When calcium carbonate is heated it decomposes.

When 5.000 g of calcium carbonate is heated, the mass of solid remaining is 2.800 g.

Calculate the mass of carbon dioxide that has been released.

Give your answer to three significant figures.

mass of carbon dioxide =_........ g

A diagram of an atom of helium is shown in Figure 9.

Explain, using Figure 9, why helium is inert.

Helium is used to fill balloons.

State one property of helium, apart from it being inert, that makes it suitable for filling balloons.

*(e) Figure 10 shows the relative amounts of three gases in the early atmosphere compared to the composition of today’s atmosphere.

Natural processes and human activities have altered the relative amounts of these gases in the atmosphere.

Explain how the relative amount of each of the gases in Figure 10 has increased or decreased over time.

This question is about gases.

When sodium is added to water, hydrogen gas is produced.

Which observation shows that a gas has been produced?

Some damp litmus paper is placed in a gas. The litmus paper is bleached.

Which gas bleaches damp litmus paper?

When calcium carbonate is heated it decomposes.

When 5.000 g of calcium carbonate is heated, the mass of solid remaining is 2.800 g.

Calculate the mass of carbon dioxide that has been released.

Give your answer to three significant figures.

mass of carbon dioxide =_........ g

A diagram of an atom of helium is shown in Figure 3.

Explain, using Figure 3, why helium is inert.

Helium is used to fill balloons.

State one property of helium, apart from it being inert, that makes it suitable for filling balloons.

Oxygen gas has the formula O₂.

Calculate the number of oxygen atoms in 3.50 mol of oxygen gas.

(Avogadro constant = 6.0210²³)

number of oxygen atoms =_........

This question is about the noble gases.

State, in terms of outer shell electrons, why the noble gases are unreactive.

Figure 1 shows an airship, filled with helium, floating above the ground.

Helium, hydrogen and krypton are gases. Figure 2 shows the reactivity and density, at room temperature and pressure, of helium, hydrogen and krypton.

The density of air is 0.001225 gcm^–3.

Helium is used in airships.

Explain why hydrogen and why krypton are not used in airships.

Mendeleev produced one of the earliest periodic tables.

State why he could not include any of the noble gases in his periodic table.

Figure 3 shows the boiling points of some of the noble gases.

Complete the bar chart to show the boiling points of neon and argon.

Predict the boiling point of xenon.

boiling point of xenon =_........ °C

Air contains several gaseous elements.

Which of these shows the three most common gaseous elements in air, listed in order from the most common to the least common?

The density of a gas can be found using the equation

A student carried out an experiment to find the density of argon.

The mass of a stopper and flask, containing no gas, was known. The flask was completely filled with argon and its mass measured.

Figure 2 shows the results the student wrote down.

Use the results to calculate the density of argon in g cm^–3.

density of argon =_........ g cm^–3

The flask used for the experiment is shown in Figure 3. The flask holds 250.0 cm³ when filled up to the line.

There is an error in the volume the student has used in the calculation. This would give an incorrect value for the density of argon.

Identify this error and state what should be done to correct it.

error_........

what should be done to correct it_........

Four of the noble gases are argon, helium, krypton and neon.

Give these gases in order of increasing density.

Much of the carbon dioxide present in the Earth’s early atmosphere dissolved into the oceans.

This led to the formation of compounds including calcium carbonate, CaCO₃.

Some of the calcium carbonate reacted with magnesium ions to form dolomite, CaMg(CO₃)₂.

Complete the ionic equation for the reaction of calcium carbonate with magnesium ions.

_........ CaCO₃ +_........ CaMg(CO₃)₂ + Ca²⁺ dolomite

P and Q are both mixtures of gases. One has the same composition as the early atmosphere and the other has the same composition as the current atmosphere.

Tests are carried out on gas mixtures P and Q.

The test for carbon dioxide is to bubble the gas into limewater; if carbon dioxide is present calcium carbonate is formed.

The results of the tests are shown in Figure 4.

Explain, using the data in Figure 4, which gas mixture represents the early atmosphere.

Complete the following sentences.

The name given to group 7 in the periodic table is_........ .

The name given to group 0 in the periodic table is_........ .

Which of the following rows gives the colours of the group 7 elements chlorine and bromine at room temperature?

Figure 2 shows the melting and boiling points of bromine and iodine.

element	melting point in C	boiling point in C
bromine	–7	59
iodine	114	184

Using the information in Figure 2, which row shows the physical states of these elements at 50C?

The densities of some elements in group 0 are shown in Figure 3.

Use the information in Figure 3 to suggest the density of krypton.

density of krypton =_........ g cm^–3

For many years, argon was used to fill filament light bulbs.

A filament light bulb is shown in Figure 4.

When the bulb is in use the metal filament becomes extremely hot.

Explain why argon, rather than air, was used to fill filament light bulbs.