Structured questions

1 There are three isotopes of neon in nature. The relative abundances of these isotopes are

shown in the following table.

Isotopes Atomic number Number of neutrons Abundance (%)

1 10 10 90.52

2 10 11 0.31

3 10 12 9.17

a) Explain the term ‘isotopes’.

b) Calculate the relative atomic mass of neon.

c) Xenon and neon belong to the same group of the periodic table.

i) State the number of electrons in the outermost shell of a xenon atom.

ii) Neon and xenon are monatomic gases. Explain why they are monatomic.

d) Suggest ONE use of neon in our daily lives.

(6 marks)

2 The table below shows some information about four elements, W, X, Y and Z.

Element Atomic number Relative atomic mass

W 11 23.0

X 13 27.0

Y 17 35.5

Z 18 40.0

a) What is the meaning of the term ‘relative atomic mass’?

b) Suppose there are only two isotopes of element Y, 35Y and 37Y. Calculate the relative

abundance of these two isotopes.

c) State, with explanation, which of the above elements

i) should be stored in paraffin oil;

ii) is used to fill a light bulb; and

iii) is used to make soft drink can.

(10 marks)

3 A part of the periodic table is shown below.

a) Across a period, the elements show a gradual change in some of their physical properties.

State ONE such property.

b) For each of the following pairs of elements, suggest ONE reaction in which they

behave

similarly.

i) Sodium and potassium

ii) Chlorine and fluorine

c) Which metal and non-metal in the above table would react most vigorously with

each

other?

d) The atomic number of krypton Kr is 36. The electronic arrangement of a krypton

atom is

2, 8, x, y. What are the values of x and y?

e) i) Caesium Cs is a Group I element. What will be observed if caesium is put into

a

tank of water?

ii) Suggest a method to store caesium in the laboratory.

(12 marks)

4 The following shows a part of the periodic table.

a) How are the elements arranged in the periodic table?

b) What is the similarity in the electronic arrangement of atoms of elements in the same

period?

c) i) According to the above periodic table, which is the most reactive metal?

ii) Suggest how the most reactive metal should be stored.

iii) State ONE hazard warning label that should be displayed on the reagent bottle

containing that metal.

d) Which of the above elements is used to make computer chips?

e) Explain why carbon has a higher melting point than iodine.

f) Suggest ONE use of chlorine in our daily lives.

g) State, with explanation, what will happen if a balloon filled with argon is released from

the top of a tower.

(11 marks)

5 The following shows a part of the periodic table.

(a to p are NOT symbols of elements.)

a) Referring to the letters indicated in the above table, answer the following questions.

i) State the name of the group elements a and i belong to.

ii) State the name of the group elements g and o belong to.

iii) In what way are the electronic arrangements of the atoms of elements c and k

(1) different from each other?

(2) similar to each other?

b) With reference to elements b and j, give an example to illustrate that

i) they have similar chemical property;

ii) they react differently from each other.

c) Which of the above elements (a to p) can be obtained by fractional distillation of

liquid

air?

d) State the difference in electrical conductivity between elements l and n.

e) Element a can be drawn to wires. Explain this with reference to its structure.

(12 marks)

6 a) Complete the following table.

Particle Atomic

number

Mass

number

Number of Electronic

arrangementprotons neutrons electrons

i) Beryllium atom 4 5

ii) Neon atom 20 2,8

iii) 13 14 13

iv) Sulphur atom 16 16

v) Potassium ion 19 39

vi) Oxide ion 8 2,8

vii) 12 12 10

viii) 19 10 2,8

ix) 11 12 10

x) 11 12 11

b) Which particle(s) in the above table is / are negatively charged?

c) In which group of the periodic table should particle (iii) be placed? Explain your

answer.

d) State the relationship between particles (ix) and (x).

(24 marks)

7 Complete the following table.

Cation Anion Compound

Name Formula Name Formula Name Formula Colour of

aqueous

solution

Sodium Na+ Bromide Br- Sodium bromide NaBr Colourless

Ammonium SO42-

Silver Ag+ AgNO3

Copper(II) Cu2+ Nitrite NO2- Blue

Fe2+ HCO3-

Potassium K+ Permanganate

Nickel(II) Ni2+ Chloride

Al3+ Iodide I-

Cr3+ Cl-

Iron(III) CrO42-

(19 marks)

8 Consider the following substances:

Water, iodine, sodium bromide, sand, mud water and diamond

a) Classify the substances into elements, compounds and mixtures.

b) Give the elements which make up the compounds in (a).

c) Which of the above substances is the hardest? Explain your choice.

d) i) Draw electron diagrams of water and sodium bromide, showing electrons in the

outermost shells only.

ii) Explain why sodium bromide is soluble in water.

iii) Explain why sodium bromide has a higher melting point than water.

(15 marks)

9 Magnesium is a Group II element of the periodic table.

a) When magnesium burns in air, magnesium oxide and a small amount of magnesium

nitride are formed.

i) Suggest a test to demonstrate that magnesium oxide is a compound and NOT a

mixture.

ii) Draw an electron diagram of magnesium nitride, showing electrons in the outermost

shells only.

b) Magnesium is a typical metal. Briefly describe the bonding in magnesium and

explain

why it can conduct electricity.

c) Strontium is another group II element. The relative atomic mass of strontium is larger

than that of magnesium.

i) In an experiment, a piece of strontium was added to a beaker of water. State TWO

observable changes for the reaction.

ii) Suggest why strontium compounds are used in fireworks.

(8 marks)

10 a) Complete the following table.

ElementAtomic

number

Mass

number

Number of

neutrons

Electron arrangement

of its atom

A 6 12

B 13 7

C 12 2, 8, 1

D 35 2, 8, 7

E 85 2, 8, 18, 8, 1

b) Classify the elements in the table into metals and non-metals.

c) i) Which two elements are in the same group of the periodic table?

ii) What is the name of the group?

iii) Which of these two elements is more reactive towards water?

d) Which two elements are isotopes?

e) Element D can form compounds X and Y with elements A and C respectively.

i) Draw electron diagrams of compounds X and Y, showing electrons in the outermost

shells only.

ii) Explain which compound has a higher melting point.

(16 marks)

11 Consider the structures of four particles below.

a) Which elements do particles W and Z represent respectively?

b) Consider particles W and X.

i) Identify the relationship between W and X.

ii) Will they react with element Z in the same way? Explain your answer.

iii) Draw an electron diagram of the compound formed between W and Z, showing

electrons in the outermost shells only.

c) Consider particles Y and Z.

i) Identify the relationship between Y and Z.

ii) Is particle Y stable? Explain your answer.

(8 marks)

12 Consider the following elements.

Element Symbol Group number

Caesium Cs I

Indium In III

Tellurium Te VI

Astatine At VII

a) Would you expect caesium to be a conductor of electricity? Explain your answer.

b) Give the chemical formula of

i) caesium sulphate;

ii) oxide of indium; and

iii) hydride of tellurium.

c) Caesium and astatine combine to form compound X.

i) Give the chemical formula of X.

ii) Will an aqueous solution of X conduct electricity? Explain your answer.

d) Astatine and hydrogen combine to form compound Y.

i) Draw an electron diagram of Y, showing the electrons in the outermost shells only.

ii) Give the chemical formula of Y.

e) Predict and explain whether X or Y is more volatile.

(13 marks)

13 The table below shows some properties of three elements in the first three periods of the

periodic table.

X Y Z

Group II IV VI

Appearance at room temperature Grey solid Shiny black

solid

Colourless

gas

Electrical conductivity at room temperature Good Good Poor

a) Classify X, Y and Z into metals and non-metals. Explain your answer.

b) What will be observed when X and Y are put into dilute hydrochloric acid separately?

c) Element Z exists as diatomic molecules in the atmosphere. The atmosphere contains

about 21% of Z by volume.

i) Explain the term ‘diatomic molecule’ with the help of an appropriate electron

diagram.

ii) Explain whether Z is very soluble in water.

d) X and Z can combine to form compound A while Y and Z combine to form compound B.

i) State the types of bond exist in A and B respectively.

ii) Write the chemical formulae of A and B.

iii) Which compound has a higher melting point? Justify your answer.

(17 marks)

14 Hydrogen (1H) and deuterium (2D) are isotopes.

a) What is the difference between a hydrogen atom and a deuterium atom?

b) When hydrogen and oxygen are mixed and ignited, water is formed. Similarly, deuterium

reacts with oxygen to form a compound called ‘heavy water’.

i) Explain why deuterium reacts with oxygen in the same way as hydrogen.

ii) Draw an electron diagram of ‘heavy water’, showing electrons in the outermost

shells only.

iii) Suggest a chemical test to show the presence of ‘heavy water’.

c) Explain why water can dissolve most ionic compounds.

(7 marks)

15 The following table shows some information of elements.

Element Number of protons Number of neutrons

W 3 4

X 7 7

Y 9 10

Z 15 16

a) Which of the above elements belong to the same group? Explain your answer.

b) i) Explain why Y exists as diatomic molecules.

ii) Draw an electron diagram for Y2, showing electrons in the outermost shells only.

c) W and X combine to form an ionic compound P. Draw an electron diagram of compound

P, showing electrons in the outermost shells only.

d) X and Y combine to form a covalent compound Q with a molecular formula of X2Y2.

i) Draw an electron diagram of compound Q, showing electrons in the outermost shells

only.

ii) State the number of lone pair electrons each atom of X in X2Y2 has.

(9 marks)

16 a) The table below shows some physical properties of Group I elements.

Element Boiling point (oC) Density (g cm-3)

Lithium 1340 0.50

Sodium 880 0.97

Potassium 460 0.86

i) State how the melting point changes in going from the top to the bottom of Group I.

ii) Suggest how all values for properties in the table are considered NOT typical of

metals in general.

iii) State ONE property of Group I elements, not given in the table, which is typical of

metals in general.

b) The diagram below shows part of a sodium chloride crystal, with one sodium ion labelled

with a positive (+) sign.

i) the diagram, mark all sodium ions with a positive (+) sign and all chloride ions

with a negative (-) sign.

ii) Explain why sodium chloride is an insulator of electricity in the solid state, but it

conducts electricity in the molten state.

c) You are provided with three unlabelled bottles each containing one of the white solids

listed below:

table salt, silicon dioxide, sugar

Outline physical tests you would use to distinguish the three substances from one another.

State also the expected observations.

(10 marks)

17 Consider the following three elements.

a) X and Y react to form a compound P with a molecular formula of X2Y2.

Draw an electron diagram of P, showing electrons in the outermost shells only.

b) Y reacts with Z to form a compound Q.

i) Draw an electron diagram of compound Q, showing electrons in the outermost

shells only.

ii) Calculate the formula mass or relative molecular mass of Q.

c) Explain whether P or Q has a higher melting point in terms of the forces between

particles.

d) Explain whether Q is soluble in water.

(9 marks)

18 The electron diagram of ammonium chloride is as follows:

(Only electrons in the outermost shells are shown.)

a) What are elements X, Y and Z?

b) i) Identify the type of bond exists between the two ions.

ii) Identify the type of bond exists between elements X and Y.

c) Does solid ammonium chloride

i) dissolve in water?

ii) conduct electricity?

Explain your answers.

d) Describe a chemical test to show the presence of chloride ions in a solid sample. State the

expected observation(s).

(13 marks)

19 Some properties of iron, sulphur and iron(II) sulphide are listed in the following table.

Iron Sulphur Iron(II) sulphide

Melting Point (oC) 1540 113 1195

Electrical conductivity in molten

state

Conductor Non-conductor Conductor

Reaction on addition of dilute

hydrochloric acid

?? No observable

change

??

a) Suggest how iron(II) sulphide can be prepared from iron and sulphur.

b) Explain the difference in melting point between sulphur and iron.

c) Explain the difference in electrical conductivity between sulphur and molten iron(II)

sulphide.

d) Explain why iron is a good conductor of heat.

e) What will be observed when iron and iron(II) sulphide are added into dilute hydrochloric

acid separately?

f) Suggest a simple method that allows you to separate iron powder from a mixture of iron

and sulphur.

(14 marks)

20 The following diagram shows a form of carbon.

a) To which group of the periodic table does carbon belong?

b) i) What is the type of structure shown in the above diagram?

ii) Based on the structure of carbon shown, suggest ONE use of it.

c) i) Is carbon in this form soluble in water? Explain your answer.

ii) Can this form of carbon conduct electricity? Explain your answer.

d) Give the name of another form of carbon.

e) When carbon is burnt in excess oxygen, a compound is formed.

i) Give the name of the compound. Suggest a chemical test to identify this compound.

ii) State and explain the difference in melting point between the compound formed and

carbon.

(13 marks)

21

a) Name the type of bonding between particles in

i) potassium bromide;

ii) silicon dioxide.

b) Draw an electron diagram of potassium bromide, showing electrons in the outermost

shells only.

c) Suggest ONE property which is different for potassium bromide and silicon dioxide.

d) Explain why silicon dioxide is a solid with a high melting point while carbon dioxide is a

gas at room temperature.

(8 marks)

22 Consider the following substances:

aluminium oxide, diamond, iodine and sodium oxide

The following flow chart is used to identify these substances.

a) Draw electron diagrams of iodine and aluminium oxide, showing electrons in the

outermost shells only.

b) Identify substances A and B.

c) Draw a labelled diagram of the experimental set-up for testing the electrical conductivity

of a substance in molten state.

d) Suggest a test which allows you to distinguish between substances C and D.

(8 marks)

23 Sodium and hydrogen react to form sodium hydride NaH.

a) Draw an electron diagram of a hydride ion H-.

b) The following diagram shows an incomplete structure of sodium hydride.

Complete the diagram by adding the missing ions.

c) i) Based on the above structure, explain why solid sodium hydride does NOT conduct

electricity.

ii) Explain why molten sodium hydride conducts electricity.

iii) Predict TWO other physical properties of sodium hydride.

d) Suggest a test which allows you to identify the presence of sodium ion in sodium hydride.

(8 marks)

24 State and explain whether the following statements are true.

a) Isotopes of the same element have the same physical properties.

b) In general, ionic bond is stronger than covalent bond.

c) Elements belonging to the same group have similar chemical properties.

d) Ionic compounds are not soluble in non-aqueous solvents.

(8 marks)

25 Consider the following table.

Substance Melting Point (oC) Electrical Conductivity

at room temperature

Electrical conductivity in

molten state

A 3550 Poor Poor

B -23 - -

C 56 Poor Poor

D 232 Good Good

E 750 Poor Good

a) Which of the above substances

i) is / are ionic compound(s)?

ii) is / are covalent compound(s) with simple molecular structure(s)?

iii) is / are metal(s)?

iv) could be diamond?

Explain your choices.

b) State whether substances A, B, C and E are soluble in water.

(16 marks)

26 “Elements in the same group of the periodic table have similar chemical properties.”

Discuss the above statement. Illustrate your answer with reactions of elements in Group II and

VII of the periodic table.

(You are required to give a paragraph-length answer. In this question, 5 marks will be awarded

for chemical knowledge and 3 marks for effective communication.)

(8 marks)

27 Below is a sketch of the melting points for some Period 3 elements.

Discuss how the melting points of the elements are related to their bondings and structures.

(You are required to give a paragraph-length answer. In this question, 6 marks will be awarded

for chemical knowledge and 3 marks for effective communication.)

(9 marks)

28 With the help of electron diagrams, describe the formation of potassium sulphide and carbon

disulphide from atoms of their elements. State, with explanation, which of the two compounds

has a higher melting point.

(You are required to give a paragraph-length answer. In this question, 9 marks will be

awarded

for chemical knowledge and 3 marks for effective communication.)

(12 marks)

29 “Potassium chloride and silicon dioxide have very different electrical conductivities and

solubilities in water.”

Discuss and explain these differences with reference to the structures of the two

compounds.

(You are required to give a paragraph-length answer. In this question, 6 marks will be

awarded

for chemical knowledge and 3 marks for effective communication.)

(9 marks)

30 Describe the bonding exists in metals. Discuss and explain FOUR physical properties of

metals with reference to the bonding in metals.

(You are required to give a paragraph-length answer. In this question, 6 marks will be

awarded

for chemical knowledge and 3 marks for effective communication.)

(9 marks)