BONDING WS 5 REVISION1

4

OCR 2009

2 This question compares the bonding, structure and properties of sodium and sodium oxide.

(a) Sodium, Na, is a metallic element.

Explain, with the aid of a labelled diagram, what is meant by the term metallic bonding.

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(b) Sodium reacts with oxygen to form sodium oxide, Na2O, which is an ionic compound.

(i) Write the equation for the reaction of sodium with oxygen to form sodium oxide.

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(ii) State what is meant by the term ionic bond.

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(iii) Draw a dot-and-cross diagram to show the bonding in Na2O.

Show outer electrons only.

[2]

Bilal Hameed BONDING WS 5

210

OCR 2009

5 The Periodic Table is a table of elements arranged in order of atomic number. The elements are classified into blocks.

(a) (i) State what is meant by the term atomic number. .................................................................................................................................... [1]

(ii) Complete the full electron configuration for a titanium atom.1s2 .............................................................................................................................. [1]

(iii) Identify the seventh element in the fourth period.

State which block this element is in.

element ..................................................... block ..................................................... [1]

(b) The figure below shows the boiling points of four hydrides of Group 6 elements.

100

0

100 H2O

H2SH2Se

H2Te

boiling point / C

(i) Explain, with the aid of a diagram, the intermolecular forces in H2O that lead to the relatively high boiling point of H2O.

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Turn over OCR 2009

(ii) Suggest why H2S has a much lower boiling point than H2O.

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(c) The boiling points of some Group 7 elements are shown below.

Group 7 element boiling point / C

chlorine 35

bromine 59

iodine 184

Explain why the halogens show this trend in boiling points.

In your answer, you should use appropriate technical terms, spelt correctly.

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TURN OVER FOR QUESTION 5(d)

Bilal Hameed BONDING WS 5

35

Turn over OCR 2009

2 Chemists have developed models for bonding and structure which are used to explain different properties.

(a) Ammonia, NH3, is a covalent compound.

(i) Explain what is meant by a covalent bond.

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(ii) Draw a dot-and-cross diagram to show the bonding in NH3.

Show outer electrons only.

[1]

(iii) Name the shape of the ammonia molecule.

Explain, using your dot-and-cross diagram, why ammonia has this shape and has a bond angle of 107.

shape: ................................................................................................................................

explanation: .......................................................................................................................

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Bilal Hameed BONDING WS 5

6 OCR 2009

(b) Ammonia reacts with hydrogen chloride, HCl, to form ammonium chloride, NH4Cl.

NH4Cl is an ionic compound containing NH4+ and Cl ions.

(i) Complete the electron configuration of the Cl ion.

1s2 .............................................................................................................................. [1]

(ii) Draw a dot-and-cross diagram to show the bonding in NH4+.

Show outer electrons only.

[1]

(iii) State the shape of, and bond angle in, an NH4+ ion.

shape: ................................................................................................................................

bond angle: ................................................................................................................. [2]

(iv) A student investigated the conductivity of ammonium chloride.

She noticed that when the ammonium chloride was solid it did not conduct electricity. However, when ammonium chloride was dissolved in water, the resulting solution did conduct electricity.

Explain these observations.

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Bilal Hameed BONDING WS 5

410

OCR 2009

4 The table below shows the melting points and atomic radii of the elements in Period 3, Na to Cl.

element Na Mg Al Si P S Cl

melting point / C 98 639 660 1410 44 113 101

atomic radius / pm 186 160 143 118 110 102 99

1 pm = 1 1012 m

(a) (i) Explain the difference in melting point for the elements Na and Mg.

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(ii) Sulfur exists as S8 molecules and chlorine as Cl 2 molecules. Use this information to explain the difference in their melting points.

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(b) Explain the decrease in the atomic radii across the period from Na to Cl.

In your answer, you should use appropriate technical terms, spelt correctly.

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[Total: 8]

Bilal Hameed BONDING WS 5

510

OCR 2010

5 This question is about elements in Period 2 of the Periodic Table.

(a) Lithium has a giant metallic structure and a boiling point of 1342 C.

Describe, with the aid of a labelled diagram, the structure and bonding in lithium and explain why lithium has a high boiling point.

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(b) Fluorine is a gas at room temperature and has a very low boiling point of 188 C.

(i) Draw a dot-and-cross diagram to show the bonding in a fluorine molecule. Show the outer electrons only.

[1]

(ii) Explain why fluorine has a low boiling point.

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Bilal Hameed BONDING WS 5

11

Turn over OCR 2010

(c) Fluorine reacts with lithium at room temperature to form a white crystalline solid, lithium fluoride. Lithium fluoride is a good conductor of electricity when molten but not when solid.

(i) Draw a dot-and-cross diagram to show the bonding in lithium fluoride. Show the outer electrons only.

[2] (ii) Explain why lithium fluoride conducts electricity when molten but not when solid.

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OCR 2010

(d) Fluorine reacts with boron, B, to form the fluoride BF3.

(i) Suggest an equation for this reaction.

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(ii) Name the shape of, and state the bond angles in, a BF3 molecule.

Explain why BF3 has this shape.

In your answer, you should use appropriate technical terms spelt correctly.

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(e) Nitrogen can also form a fluoride, NF3, which has a permanent dipole.

Explain why NF3 has a permanent dipole.

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12

OCR 2010

(d) Fluorine reacts with boron, B, to form the fluoride BF3.

(i) Suggest an equation for this reaction.

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(ii) Name the shape of, and state the bond angles in, a BF3 molecule.

Explain why BF3 has this shape.

In your answer, you should use appropriate technical terms spelt correctly.

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(e) Nitrogen can also form a fluoride, NF3, which has a permanent dipole.

Explain why NF3 has a permanent dipole.

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12

OCR 2010

(d) Fluorine reacts with boron, B, to form the fluoride BF3.

(i) Suggest an equation for this reaction.

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(ii) Name the shape of, and state the bond angles in, a BF3 molecule.

Explain why BF3 has this shape.

In your answer, you should use appropriate technical terms spelt correctly.

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(e) Nitrogen can also form a fluoride, NF3, which has a permanent dipole.

Explain why NF3 has a permanent dipole.

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12

OCR 2010

(d) Fluorine reacts with boron, B, to form the fluoride BF3.

(i) Suggest an equation for this reaction.

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(ii) Name the shape of, and state the bond angles in, a BF3 molecule.

Explain why BF3 has this shape.

In your answer, you should use appropriate technical terms spelt correctly.

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(e) Nitrogen can also form a fluoride, NF3, which has a permanent dipole.

Explain why NF3 has a permanent dipole.

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OCR 2010

(f) Describe and explain the trend in atomic radii of the elements Li to F across Period 2 of the Periodic Table.

In your answer, you should use appropriate technical terms, spelt correctly.

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[Total: 21]

END OF QUESTION PAPER

12

OCR 2010

(d) Fluorine reacts with boron, B, to form the fluoride BF3.

(i) Suggest an equation for this reaction.

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(ii) Name the shape of, and state the bond angles in, a BF3 molecule.

Explain why BF3 has this shape.

In your answer, you should use appropriate technical terms spelt correctly.

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(e) Nitrogen can also form a fluoride, NF3, which has a permanent dipole.

Explain why NF3 has a permanent dipole.

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Bilal Hameed BONDING WS 5

66

OCR 2010

3 This question is about different models of bonding and molecular shapes.

(a) Magnesium sulfide shows ionic bonding.

(i) What is meant by the term ionic bonding?

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(ii) Draw a dot-and-cross diagram to show the bonding in magnesium sulfide. Show outer electron shells only.

[2]

(b) Dot-and-cross diagrams can be used to predict the shape of covalent molecules.

Fluorine has a covalent oxide called difluorine oxide, F2O. The oxygen atom is covalently bonded to each fluorine atom.

(i) Draw a dot-and-cross diagram of a molecule of F2O. Show outer electron shells only.

[2]

Bilal Hameed BONDING WS 5

7Turn over OCR 2010

(ii) Predict the bond angle in an F2O molecule. Explain your answer.

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(c) Liquid ammonia, NH3, and water, H2O, both show hydrogen bonding.

(i) Draw a labelled diagram to show hydrogen bonding between two molecules of liquid ammonia.

[3]

(ii) Water has several anomalous properties as a result of its hydrogen bonding.

Describe and explain one anomalous property of water which results from hydrogen bonding.

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[Total: 13]

7

Turn over OCR 2010

(ii) Predict the bond angle in an F2O molecule. Explain your answer.

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(c) Liquid ammonia, NH3, and water, H2O, both show hydrogen bonding.

(i) Draw a labelled diagram to show hydrogen bonding between two molecules of liquid ammonia.

[3]

(ii) Water has several anomalous properties as a result of its hydrogen bonding.

Describe and explain one anomalous property of water which results from hydrogen bonding.

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[Total: 13]

Bilal Hameed BONDING WS 5

810

OCR 2011

5 Chlorine, bromine and iodine are halogens commonly used in school and college experiments.

(a) Halogens have van der Waals forces between their molecules.

(i) Describe how van der Waals forces arise.

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(ii) State and explain the trend in the boiling points of chlorine, bromine and iodine.

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(b) The halogen astatine does not exist in large enough quantities to observe any of its reactions.

Why would astatine be expected to react similarly to other halogens?

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Bilal Hameed BONDING WS 5

96

OCR 2012

2 Chemists can use the Periodic Table to predict the behaviour of elements.

(a) What is the name of the term used to describe the repeating patterns in the Periodic Table?

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(b) Melting points show a trend across a period.

The table below shows the melting points of three elements in Period 3 of the Periodic Table.

element aluminium silicon phosphorus

melting point / C 660 1410 44

Explain the trend shown in terms of bonding and structure.

In your answer, you should use appropriate technical terms spelled correctly.

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4

OCR 2012

(g) A student heats 12.41 g of hydrated sodium thiosulfate, Na2S2O35H2O, to remove the water of crystallisation. A white powder called anhydrous sodium thiosulfate forms.

(i) What does the term anhydrous mean?

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(ii) What is the relative formula mass of Na2S2O35H2O?

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(iii) Calculate the expected mass of anhydrous sodium thiosulfate that forms.

mass = ...................................................... g [2]

(h) Sulfur hexafluoride, SF6, exists as non-polar covalent molecules with an octahedral shape.

(i) Explain why a molecule of SF6 has an octahedral shape. ...........................................................................................................................................

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(ii) Fluorine has a higher electronegativity than sulfur, yet SF6 molecules are non-polar. Explain what is meant by the term electronegativity and suggest why SF6 molecules are

non-polar.

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Bilal Hameed BONDING WS 5

7Turn over OCR 2012

(c) Scientists use sketch graphs to show trends.

(i) Draw a sketch graph to show the general trend in ionisation energy across Period 3.

Na

ionisationenergy

Mg Si ArP SAl Cl [1]

(ii) Draw a sketch graph to show the general trend in atomic radius across Period 3.

Na

atomicradius

Mg Si ArP SAl Cl [1]

[Total: 9]

Bilal Hameed BONDING WS 5

1011

Turn over OCR 2012

(b) The hydrazine molecule, H2NNH2, is covalent.

Predict the HNH bond angle in a hydrazine molecule.

Explain your answer.

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(c) Like ammonia, hydrazine is a base that reacts with water to form negative and positive ions.

(i) Write the formula of the negative ion that is formed when hydrazine reacts with water.

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(ii) Suggest the formula of a positive ion which might form when hydrazine reacts with water.

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TURN OVER FOR QUESTION 5(d)

Bilal Hameed BONDING WS 5