Group 1: the alkali metals

Potassium is in Group 1 of the periodic table.

What name is given to Group 1 elements?

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A potassium atom is very small.

What is the radius of a potassium atom?

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What name is given to the number of protons in an atom?

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Table 1 shows the name and the relative charge of the particles in a potassium atom.

Complete Table 1.

The electronic structure of a potassium atom is 2,8,8,1

Figure 1 represents the electronic structure of a potassium ion.

What is the charge on a potassium ion ?

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Figure 2 shows the melting points of some Group 1 elements.

Predict the melting point of potassium.

Potassium has two isotopes.

Table 2 shows the percentage (%) abundance of the two isotopes.

How is the relative atomic mass (A_r) of potassium calculated?

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Sodium is in Group 1 of the periodic table. Sodium reacts with oxygen to produce sodium oxide.

Balance the equation for the reaction.

Explain what happens to sodium atoms and to oxygen atoms when sodium reacts with oxygen to produce sodium oxide (Na₂O). Answer in terms of electrons.

Sodium burns in a gas jar of oxygen. Figure 3 shows the apparatus.

Give two observations seen during the reaction.

Describe two differences in the observations if potassium is used instead of sodium.

This question is about Group 1 elements.

What are the Group 1 elements known as? Tick (✓) one box.

Figure 1 shows a lithium atom.

What is the number of electrons and neutrons in the atom of lithium?

What is the relative charge on a lithium ion? Tick (✓) one box.

Lithium is heated and then cooled in an experiment.

Two physical changes happen in the experiment. Draw one line from each stage to the physical change that happens in that stage.

Figure 2 represents the melting points of some Group 1 elements.

Figure 2

What is the melting point of caesium? Use Figure 2.

The melting point of potassium is 63 °C Draw a bar for the melting point of potassium on Figure 2.

Describe the trend of the melting points of the Group 1 elements in Figure 2.

The boiling point of sodium is 883 °C What is the state of sodium at 150 °C? Use Figure 2. Tick (✓) one box.

Figure 3 represents the electronic structure of a sodium atom and of a potassium atom.

Complete the sentence. Choose the answer from the box.

Potassium is more reactive than sodium because potassium more

Sodium and potassium are Group 1 elements.

What is the name of Group 1 elements? Tick (✓) one box.

Figure 5 represents the melting points of Group 1 elements.

What is the melting point of sodium?

Sodium reacts with water to produce sodium hydroxide and hydrogen. Balance the equation for the reaction.

Calculate the relative formula mass (M_r) of sodium hydroxide (NaOH). Relative atomic masses (A_r): H = 1 O = 16 Na = 23

Sodium and potassium both react with water. Figure 6 shows sodium reacting with water.

Compare what is seen when sodium reacts with water and when potassium reacts with water.

This question is about elements in the periodic table.

What property was used to arrange elements in early periodic tables? Tick (✓) one box.

In early periodic tables, iodine (I) was placed before tellurium (Te). Mendeleev placed iodine after tellurium. Figure 7 shows part of Mendeleev’s periodic table.

Suggest one reason why Mendeleev placed iodine in the column shown in Figure 7.

Table 3 shows the melting points of three Group 1 metals.

What state is lithium at 100 °C? Use Table 3. Tick (✓) one box.

Complete the graph in Figure 8. Use Table 3. You should:

• complete the scale on the y-axis

• draw bars to show the melting points of sodium and potassium.

Figure 8

Lithium reacts with chlorine to produce lithium chloride. Figure 9 shows what happens to the electrons in the outer shells when a lithium atom reacts with a chlorine atom. The dots (o) and crosses (x) represent electrons.

Describe what happens to a lithium atom and to a chlorine atom when they react. Use Figure 9 to answer in terms of electrons.

Lithium and potassium are in the same group of the periodic table. Figure 10 represents the electronic structures of a lithium atom and of a potassium atom.

Give two reasons why potassium is more reactive than lithium.

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

Explain what happens to caesium atoms and to oxygen atoms when caesium reacts with oxygen to produce caesium oxide. You should answer in terms of electrons.

Explain why caesium is more reactive than sodium. You should answer in terms of electrons.

Figure 6 shows part of Mendeleev’s periodic table.

Explain why the early periodic tables placed iodine (I) before tellurium (Te), but then Mendeleev placed tellurium before iodine.

This question is about Group 1 elements.

Sodium reacts with chlorine to produce sodium chloride. Balance the equation for the reaction.

4.6 g of sodium reacts with chlorine to produce 11.7 g of sodium chloride. What mass of chlorine reacted?

A teacher puts hot sodium into a gas jar of chlorine. The changes seen before, during and after this reaction were observed. Complete the sentences. Choose the answers from the box.

Sodium chloride (NaC l) is an ionic compound. Write the formulae of the ions in sodium chloride.

Complete the sentence. Choose the answer from the box.

Potassium is more reactive than sodium.

How does the size of a potassium atom compare with the size of a sodium atom? Give a reason for your answer.

This question is about sodium.

Sodium reacts with chlorine. What is the balanced equation for the reaction?

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Hot sodium is put in a gas jar of chlorine. Describe the observations made before, during and after the reaction.

Explain why sodium is less reactive than potassium.

Chlorine reacts with sodium and with hydrogen. Compare the structure and bonding in sodium chloride and hydrogen chloride.