Arrangement of Elements (Cambridge (CIE) O Level Chemistry): Theory Questions

An element, M, has the electron distribution 2 + 8 + 8 + 3.

Which group in the Periodic Table is element M likely to be in?

Predict whether element M is a poor or a good conductor of electricity.

Give a reason for your answer.

Binary compounds contain two atoms per molecule, for example HCl.
Identify an element which could form a binary compound with element M.

Extended Only

Predict the formula of the sulfate of M. The formula of the sulfate ion is SO₄ ^2-.

Extended Only

The hydroxide of M is a white powder which is insoluble in water.
Describe how you could show that this hydroxide is amphoteric.

For each of the following, name an element which matches the description.

It is the only non-metal which is a good conductor of electricity.

Inert electrodes are made from this metal.

An element which can form an ion of the type X^3–.

It has the same electron distribution as the calcium ion, Ca²⁺.

The element is in Period 5 and Group VI.

Element Z is in Period 3 and Group V.

Identify element Z.

Helium, neon and argon are noble gases.

Explain, in terms of the electronic structure, why neon is unreactive.

Copper is a transition element. It can have variable oxidation states.

State two other chemical properties of transition elements which make them different from Group I elements.

Aqueous chlorine reacts with aqueous magnesium bromide. 

Cl₂ + MgBr₂ → Br₂ + MgCl₂ 

How does this reaction show that chlorine is more reactive than bromine?

What colour is bromine in aqueous solution?

Complete the word equation to show the halogen and halide compound which react to form the products iodine and sodium chloride. 

Explain, in terms of the reactivity of the halogens, why aqueous bromine will not react with aqueous sodium chloride.

The symbols of the elements in Period 2 of the Periodic Table are shown. 

Li  Be  B  C  N  O  F  Ne

For each of the following, give the symbol of an element from Period 2 which matches the description.

Each element may be used once, more than once or not at all.

Which element has atoms with only two electrons in the outer shell?

Which element is a monoatomic gas?

Which element is a soft metal stored in oil?

Which element has atoms with only seven protons?

A list of substances is shown.

aluminium oxide

diamond

carbon dioxide

copper

chlorine

hydrogen

ethanol

ethene

nitrogen monoxide

oxygen

sodium

sulfur dioxide

Answer the following questions about these substances. Each substance may be used once, more than once or not at all.

State which substance:

is an amphoteric oxide

is discharged at the cathode in the electrolysis of aqueous copper sulfate

has a melting point similar to silicon(IV) oxide

is a harmful gas reduced in the catalytic converter from a car

has more than one oxidation number

reacts with hydrogen in presence of a nickel catalyst

has ions arranged in a lattice which are attracted to a sea of delocalised electrons

turns limewater milky

needs to be extracted by electrolysis from its ore

The table below shows the elements in the third period of the Periodic Table, the number of electrons in their outer energy  level, their oxidation state in their common compounds and their melting points.

Describe and explain the variation in oxidation state across the period.

The first three elements, Na, Mg and Al, are metals.

Describe the structure of a typical metal.

Explain why Na, Mg and Al are good conductors of electricity.

Which element exists as diatomic molecules of the type X₂?

Silicon has a similar structure to diamond.

Explain why silicon has the highest melting point in the period.

Sodium chloride is a crystalline solid with a high melting point. It dissolves in water to give a neutral solution. Phosphorus trichloride is a liquid at room temperature. It reacts with water to form an acidic solution.

Suggest an explanation for these differences in properties.

Describe how you could show that magnesium oxide is a basic oxide and not an amphoteric oxide.

Draw a dot-and-cross diagram showing the bonding in magnesium oxide. Show outer electrons only.

The table below includes information about some of the elements in Period 2.

Why does neon exist as single atoms but fluorine exists as molecules?

What determines the order of the elements in a period?

When liquid nitrogen boils the following change occurs.

N₂(l) → N₂(g)

The boiling point of nitrogen is very low even though the bond between the atoms in a nitrogen molecule is very strong. Suggest an explanation.

Draw a diagram showing the arrangement of the outer shell (valency) electrons in a molecule of nitrogen.

Use your copy of the Periodic Table to help you answer some of these questions.

Predict the formulae of the following compounds.

i) nitrogen fluoride .........................

ii) phosphorus sulfide ...................

Deduce the formulae of the following ions.

i) Selenide 

ii) Gallium 

Use the following ions to determine the formulae of the compounds.        

ions    OH^–    Cr³⁺    Ba²⁺    SO₄^2–

compounds

i) Chromium(III) sulfate 

ii) Barium hydroxide 

In the Periodic Table, the elements are arranged in columns called Groups and in rows called Periods.

i) Complete the table for some of the elements in Period 3.

[2]

ii) What is the relationship between the group number and the number of valency electrons?

[1]

iii) Explain the relationship between the number of valency electrons and the valency:

For the elements Na to Al,
For the elements P to Cl.

[4]

Across a period, the elements change from metallic to non-metallic.

i) Describe how the type of oxide changes across this period.

[2]

ii) Describe how the type of bonding in the chlorides formed by these elements changes across this period.

[2]