International ASChemistryEdexcelExam Questions1. Structure, Bonding & Introduction to Organic Chemistry1.7 Covalent Bonding & Structure

Covalent Bonding & Structure (Edexcel International AS Chemistry)

Exam Questions

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1.7 Covalent Bonding & Structure

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1.7 Covalent Bonding & Structure

1a2 marks

This question is about the chlorides of beryllium and calcium.

Complete the electronic configurations of the atoms of beryllium and calcium using the s, p, d notation.

Be 1s2

Ca 1s2

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1b2 marks

In the gaseous state, beryllium chloride is molecular.

Draw a dot-and-cross diagram to show the bonding in a molecule of beryllium chloride, BeCl2.

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1c2 marks

In the solid state, beryllium chloride forms a polymeric structure.

The diagram shows part of this structure.

q12c-paper-1-oct-2021-edexcel-ial-chemistry

The diagram uses lines and arrows to represent the two different types of covalent bond.

Describe how each type of bond is formed.

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1d4 marks

The Cl—Be—Cl bond angle is different in the two forms of beryllium chloride.

Predict the two bond angles, justifying your answers by referring to electron-pair repulsion theory.

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1e2 marks

Anhydrous calcium chloride is a crystalline, ionic solid which melts at 772°C.

Draw a dot-and-cross diagram for calcium chloride.
Show the outer electrons only.

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1f3 marks

Explain why gaseous beryllium chloride and solid calcium chloride have different types of bonding.

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2a3 marks

This question is about the structure and bonding of Group 5 chlorides.

Nitrogen trichloride, NCl3, has a molecular structure.

The displayed formula of a molecule of NCl3 is shown.

q19a-paper-1-jan-2021-edexcel-ial-chemistry

Complete the table for this molecule.

Number of bond pairs around N atom  
Number of lone pairs around N atom  
Cl-N-Cl bond angle  
Name of shape of molecule  

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2b4 marks

Under standard conditions, phosphorus(V) chloride (PCl5) is a solid made up of PCstraight l subscript 4 superscript plus cations and PCbegin mathsize 16px style l subscript 6 to the power of minus sign end style anions.

Antimony(V) chloride (SbCl5) is a liquid made up of SbCl5 molecules.

i)
Explain why PCl5 has a higher melting temperature than SbCl5.

(2)

ii)
Draw a dot-and-cross diagram to show the bonding in a molecule of SbCl5.
Use dots (•) to represent the Sb electrons, and crosses (x) to represent the Cl electrons. Show outer electrons only.

(2)

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2c2 marks

At low temperatures, SbCl5 converts to Sb2Cl10 which contains dative covalent bonds.

i)
State what is meant by the term dative covalent bond.

(1)

ii)
Complete the diagram to show the dative covalent bonds in Sb2Cl10 .

(1)

q19c-ii-paper-1-jan-2021-edexcel-ial-chemistry

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2d1 mark

Arsenic also forms a pentachloride with the formula AsCl5.

Give one possible reason why nitrogen is the only Group 5 element that does not form a pentachloride.

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3a4 marks

This question is about the bonding in the elements of Period 3 in the Periodic Table.
The melting temperatures of the Period 3 elements are shown in the table.

Element Na Mg Al Si P S Cl Ar
Melting
temperature / °C		 98 650 660 1423 44 120 −101 −189

Sodium, magnesium and aluminium are metals.

i)
State what is meant by metallic bonding.

(1)

ii)

Melting temperature depends on the strength of metallic bonding.

Explain why the metallic bonding in magnesium is much stronger than that in sodium.

(3)

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3b4 marks
i)

In the elements silicon, phosphorus, sulfur and chlorine, the atoms are joined by covalent bonds.

Describe the attraction between the atoms in a covalent bond.

(1)

ii)

Explain why the melting temperature of silicon is much higher than that of phosphorus, by referring to their structures.

(3)

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3c5 marks

Sulfur reacts with chlorine to form sulfur dichloride, SCl2.

i)
Complete the dot-and-cross diagram of a molecule of sulfur dichloride.
Use dots (•) for the chlorine electrons and crosses (×) for the sulfur electrons.
Show the outer shell electrons only.

(2)

q22c-i-paper-1-jan-2022-edexcel-ial-chemistry

ii)
Suggest a value for the Cl–S–Cl bond angle. Justify your answer.

(3)

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