Group 1: the alkali metals

Lithium is an alkali metal.

State which group of the periodic table contains the alkali metals.

Which of the following is a property of lithium?

A teacher adds a small piece of lithium to water containing universal indicator.

The universal indicator changes colour.

State the colour change shown by the universal indicator.

When lithium is added to water, lithium hydroxide and a gas are produced.

What is the name of the gas produced in this reaction?

Lithium hydroxide contains lithium ions, Li⁺.

Describe how a lithium atom becomes a lithium ion.

Calculate the percentage by mass of hydrogen in lithium hydroxide, LiOH.

(relative atomic masses: Li = 7, O = 16, H = 1.0)

Group 1 elements are known as the alkali metals.

Which row gives two physical properties of the alkali metals?

The alkali metals react with water.

A teacher adds a small piece of potassium to water.

Give two observations that would be seen.

The reaction of lithium with water is much less vigorous than the reaction of potassium with water.

Explain why, in terms of their electronic configurations.

When sodium reacts with water, a solution of sodium hydroxide is formed.

When the solution is left in air, the hydroxide ions react with carbon dioxide, forming carbonate ions, CO₃^2–, and one other product.

Complete the ionic equation for this reaction.

_........ OH^– +_........ CO₃^2– +_........

The relative atomic mass of caesium is 132.905.

Calculate the average mass of one atom of caesium

(Avogadro constant = 6.02 × 10²³)

mass =_........ g

This question is about the metals and non-metals in period 3 of the periodic table.

Figure 1 shows some data about some of the elements in period 3.

Use the periodic table to answer these questions.

Give the name of the element in period 3 that is not shown in Figure 1.

Give the relative atomic mass of silicon.

State which metal and which non-metal in Figure 1 have the lowest melting points.

metal with lowest melting point

non-metal with lowest melting point

Alkali metals react with water to produce an alkaline solution and hydrogen gas.

A test tube of gas can be tested to see if the gas is hydrogen by putting a lighted splint at the top of the test tube.

A student suggests the following method to show that an alkaline solution and hydrogen gas are produced in this reaction.

step 1pour 150 cm³ water into the container shown in Figure 2

step 2 add a small piece of lithium to the water in the container shown in Figure 2

step 3 hold a lighted splint above the container

step 4 hold some damp red litmus paper above the mixture in the container

Give the name of the container shown in Figure 2.

A teacher says that step 3 and step 4 will not work to show that hydrogen gas and an alkaline solution are produced in the reaction.

Explain one change that could be made in each step to make the method work.

step 3_........

The relative atomic mass of argon is 40 and the relative atomic mass of potassium is 39 but potassium appears after argon in the periodic table.

State why potassium appears after argon in the periodic table.

Potassium reacts with water to form two products.

Give the formulae of both products.

_........ and_........

The reaction of potassium with water is exothermic.

On Figure 6, draw and label the reaction profile diagram for this reaction, labelling the activation energy.

Some reactions are endothermic.

Explain, in terms of bond breaking and bond forming, why some reactions are endothermic.

Figure 13 shows some information about some group 1 metals.

Explain, in terms of their electronic configurations, why these metals are placed in group 1 of the periodic table.

Which row shows two correct properties of group 1 metals?

The word equation for the reaction of potassium with bromine is

potassium + bromine potassium bromide

Add the missing state symbol and balance the equation for this reaction.

_........ K(_........ ) + Br₂(g) _........ KBr(s)

A sample of potassium contains three isotopes, potassium-39, potassium-40 and potassium-41.

Explain the meaning of the term isotopes.

*(e) The reactivity of the group 1 metals increases from lithium to caesium.

Often, teachers demonstrate the reactions of lithium, sodium and potassium with water.

These reactions can be used to predict the behaviour and reactions of rubidium and caesium with water.

Describe the reactions of each of the group 1 metals with water including the predicted behaviour and reactions of rubidium and caesium.

You may use word equations in your answer.

Figure 4 shows some information about the group 1 metals.

Explain, in terms of their electronic configurations, why these metals are placed in group 1 of the periodic table.

Which row shows two correct properties of group 1 metals?

The word equation for the reaction of potassium with bromine is

potassium + bromine potassium bromide

Add the missing state symbol and balance the equation for this reaction.

A sample of potassium contains three isotopes, potassium-39, potassium-40 and potassium-41.

Explain the meaning of the term isotopes.

This sample of potassium contains

93.25% potassium-39

0.02% potassium-40

6.73% potassium-41

Calculate the relative atomic mass of this sample of potassium.

This question is about elements in group 1 of the periodic table.

Figure 1 shows the symbols of the first three elements in group 1 of the periodic table and their melting points.

Use the periodic table to answer these questions.

Give the symbol of another element in group 1.

Give the atomic number of lithium.

Describe the trend in the melting points of the elements in Figure 1.

The elements in group 1 react very vigorously with water.

A student suggests this method to see what happens when sodium reacts with water.

step 1 put on safety glasses and a laboratory coat

step 2 cut a 2 cm×2 cm2 cm cube of sodium

step 3 put a few drops of water in the container shown in Figure 2

step 4 add the sodium to the water in the container and observe the reaction

Figure 2 shows a diagram of the container the student suggested for step 3.

Give the name of the container shown in Figure 2.

A teacher says that the method is not safe because the reaction is too vigorous.

Explain changes that could be made to step 2 and to step 3 that would make the method safer.

step 2: change and explanation

step 3: change and explanation

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 potassium and zinc.

Which of the following temperatures is most likely to be the melting point of potassium?

Explain how the electronic configuration of an atom of potassium is related to its position in the periodic table.

Potassium reacts with oxygen to form potassium oxide.

Describe the test to show that a gas is oxygen.

Potassium oxide is ionic.

Write the electronic configurations for the ions in potassium oxide, K₂O.

potassium ion:_........

oxide ion:_........

Figure 4 shows two gas syringes connected by a glass tube.

Inside the glass tube there are some pieces of zinc. Zinc reacts with oxygen at a temperature of over 225 °C. Not all the oxygen reacts at once, the oxygen reacts only when in contact with the zinc.

Devise a plan to find the volume of oxygen contained in a known volume of air, using the apparatus shown in Figure 4.

This question is about some of the elements in group 7 of the periodic table.

Which row in the table correctly shows the colours and physical states of the elements at room temperature?

The compound phosphorus oxychloride has the formula POCl₃.

Calculate the percentage by mass of chlorine in phosphorus oxychloride.

(relative atomic masses: O = 16.0, P = 31.0, C l = 35.5)

percentage by mass of chlorine =_........

When iron reacts with chlorine, iron chloride is formed.

Two possible equations for this reaction are

A Fe + Cl₂ FeCl₂ B 2Fe + 3Cl₂ 2FeCl₃

In an experiment, 8.40 g iron reacts with chlorine to form 19.05 g iron chloride.

Show, using a calculation, which reaction, A or B, is taking place.

You must show your working.

(relative atomic masses: C l = 35.5, Fe = 56.0)

*(d) Group 1 metals react with the elements from group 7 to form salts.

Some examples of these reactions are shown in Figure 7.

You will find the position of these elements in their groups on the periodic table.

Explain, in terms of their electronic configurations and the relative reactivity of these elements, which of the reactions shown in Figure 7 would be the most violent.

An atom of potassium has atomic number 19 and mass number 39.

Give the electronic configuration of this potassium atom.

This potassium atom forms the ion K⁺.

Which row shows the number of protons and the number of neutrons in this potassium ion, K⁺?

Potassium and caesium are in the same group of the periodic table.

Explain, in terms of electrons, why potassium and caesium are in the same group.

Fluorine boils at –188C. There are forces between fluorine molecules.

Explain, in terms of these forces, why the boiling point of fluorine is low.

Potassium reacts with fluorine to form potassium fluoride. Potassium fluoride is a solid.

Complete the balanced equation for this reaction and add the state symbols.

_........ K (_........ ) + F₂(g) _........ KF (_........ )

What are the elements in group 1 of the periodic table called?

Figure 9 shows the melting points and boiling points of elements in group 7 of the periodic table.

Give, using Figure 9, the boiling point of bromine.

boiling point of bromine =_........ C

State which two elements from Figure 9 are solids at room temperature.

The first four elements in group 1 are lithium, sodium, potassium and rubidium.

Rubidium reacts with water to form rubidium hydroxide and hydrogen.

Predict what you would see when a small piece of rubidium is placed in a large volume of water.

Why is rubidium more reactive than potassium?

8.5 g of rubidium are reacted completely with water.

The reaction makes a solution of rubidium hydroxide. The volume of this solution is 2.5 dm³.

Calculate the concentration of the rubidium hydroxide solution in g dm^–3.

(relative atomic mass: Rb = 85; relative formula mass: RbOH = 102)

concentration =_........ g dm^–3

An example of an endothermic reaction is the reaction between rubidium hydroxide and ammonium carbonate, (NH₄)₂CO₃.

This reaction forms rubidium carbonate, Rb₂CO₃, ammonia and one other product.

Write the balanced equation for this reaction.

Some of the elements in the periodic table are metals.

The electronic configuration of a metal is 2.8.3

Which row shows the group and period of the periodic table where this metal is found?

Lithium, potassium and rubidium are alkali metals.

Describe what you would see when a small piece of rubidium is dropped on to water.

The electronic configuration of lithium is 2.1 The electronic configuration of potassium is 2.8.8.1 Lithium is less reactive than potassium.

Explain, in terms of their electronic configurations, why lithium is less reactive than potassium.

Lithium has two naturally occurring isotopes, lithium‑6 and lithium‑7.

A sample of lithium contains 7.59 % of lithium‑6 92.41% of lithium‑7.

Calculate the relative atomic mass of lithium in this sample.

Give your answer to two decimal places. You must show your working.

relative atomic mass of lithium =_........

Lithium, sodium and potassium are reactive metals in group 1 of the periodic table.

Sodium metal tarnishes in air to form a layer of sodium oxide on its surface. 0.92 g of sodium combined with 0.32 g of oxygen in this oxide.

Calculate the empirical formula of this sodium oxide. (relative atomic masses: O = 16, Na = 23)

You must show your working.

empirical formula of sodium oxide =_........

Sodium reacts with water to form sodium hydroxide in solution and hydrogen.

Complete the balancing of the equation for this reaction and add the state symbols for each substance.

_........ Na(_........ ) + 2H₂O(_........ ) _........ NaOH(_........ ) + H₂(_........ )

In an experiment equal-sized pieces of lithium, sodium and potassium are added to separate samples of water.

A flame is produced only with potassium because potassium

Lithium, sodium and potassium are reactive metals in group 1 of the periodic table.

Sodium metal tarnishes in air to form a layer of sodium oxide on its surface. 0.92 g of sodium combined with 0.32 g of oxygen in this oxide.

Calculate the empirical formula of this sodium oxide. (relative atomic masses: O = 16, Na = 23)

You must show your working.

empirical formula of sodium oxide =_........

Sodium reacts with water to form sodium hydroxide solution and hydrogen.

Complete the balancing of the equation for this reaction and add the state symbols for each substance.

_........ Na(_........ ) + 2H₂O(_........ ) _........ NaOH(_........ ) + H₂(_........ )

In an experiment equal-sized pieces of lithium, sodium and potassium are added to separate samples of water.

A flame is produced only with potassium because potassium

Explain, in terms of electronic configurations, the increase in reactivity from lithium to sodium to potassium.