Bonding (OCR GCSE Chemistry A (Gateway))

This question is about structure and bonding.

Look at the two structures, A and B, in Fig. 22.1.

i) Identify the bonding in structure A.

Explain your answer.

Bonding ..............................................................................

Explanation .......................................................................

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ii) Explain why structure B has a high melting point.

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iii) Explain why structure B does not conduct electricity.

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Look at the structure of a metal in Fig. 22.2. Metals are malleable, which means they can be hammered or pressed into shape without breaking or cracking.

Explain why metals are malleable.

Dmitri Mendeleev produced a Periodic Table of elements which is the basis for our modern Periodic Table. He left gaps for elements that had not been discovered yet as shown in Fig. 23.1.

Describe two ways Mendeleev arranged the elements in his Periodic Table.

Describe how the elements are arranged in the modern Periodic Table.

Mendeleev left gaps in his Periodic Table for undiscovered elements. He predicted properties of these elements.

Table 23.1 shows the predicted properties for one of these elements in one of the gaps.

Mendeleev called this element ‘eka-silicon’.

Table 23.1

Table 23.2 shows some of the elements that were discovered after Mendeleev published his Periodic Table.

Table 23.2

i) Which element matches Mendeleev’s predictions for ‘eka-silicon’? Tick () one box.

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ii) Give two reasons for your answer to (c)(i).

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i) Mendeleev did not predict the existence of argon, neon, krypton or xenon.

The electron arrangement of argon is 2,8,8.

What does this tell you about the reactivity of argon?

Explain your answer.

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ii) Neon is an element that has isotopes. Two of the isotopes are shown below.

Complete Table 23.3 to show the number of protons, neutrons and electrons in each neon isotope.

Table 23.3

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Look at the diagram.

It shows part of Mendeleev’s Periodic Table which was developed in 1871.

Mendeleev arranged the elements in order of relative atomic mass.

Describe the differences between Mendeleev’s Periodic Table and the modern-day version.

Metal elements and non-metal elements have different physical properties.

The table shows the physical properties of some elements.

i) Which element, A, B, C or D, would be best to use for cables in overhead pylons to transfer electricity?

Tick (✓) one box.

A   

B    

C   

D   

Explain your answer.

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ii) What is meant by physical property?

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Element C burns in oxygen to make white clouds of its oxide.

Describe how you could test the oxide to find out if the element is a metal.

Higher Only 

i) Chlorine is a non-metal.

Chlorine has two common isotopes.

Look at the information about the common isotopes of chlorine.

Complete the table to show the atomic structure for each isotope of chlorine.

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ii) Chlorine gas, C₂, reacts with barium, Ba.

Barium chloride, BaC₂, is made.

Write a balanced half equation for chlorine in this reaction.

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iii) Barium chloride solution reacts with sodium sulfate solution, Na₂SO₄.

A white precipitate of barium sulfate, BaSO₄, is made.

Write a balanced ionic equation to show the formation of barium sulfate.

Include state symbols.

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