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A-Level CAIE Chemistry AS9.1 Periodicity of physical properties of the elements in Period 3Question Bank

[Maximum number: 3]

Sodium and magnesium are the first two elements in the third period.

(a)

Group 2 elements, including magnesium, react with oxygen and with dilute acids. There are trends in both the physical and chemical properties of the elements and their compounds down the group. Reactivity generally increases from Mg to Ba .

[ 3 ]
(i)

Suggest why there is a general decrease in the melting points of the elements down Group 2.

[ 3 ]
[Maximum number: 2]

Group 2 metals form alkaline solutions in water.

(a)

The table shows the melting points of some Group 2 metal oxides.

Table

Explain the trend in the melting points of the oxides down Group 2.

[ 2 ]
[Maximum number: 4]

The elements silicon, phosphorus and sulfur are in Period 3 of the Periodic Table.

(a)
(i)

Describe the variation in atomic radius from silicon to sulfur.

[ 1 ]
(ii)

The melting point of silicon is 1410∘C1410^{\circ} \mathrm{C}. The melting point of sulfur is 113∘C113^{\circ} \mathrm{C}.

Explain this difference.

[ 3 ]
(a)

（d）Fig． 1.1 shows the variation in melting point of some Period 3 elements in their standard states at room temperature and pressure．

Fig． 1.1

Fig． 1.1

[ 2 ]
(i)

Complete Fig. 1.1 to show the variation in the melting points of the elements P, S and C 1 .

[ 2 ]
(a)
(i)

Describe the trend in the solubility of the hydroxides of magnesium, calcium and strontium.

Explain your answer. > >
most soluble
least soluble

[ 4 ]
[Maximum number: 1]

Which element has the second smallest atomic radius in its group and the second highest electrical conductivity in its period?

A

boron

B

calcium

C

magnesium

D

sodium

[Maximum number: 4]

The table gives some data for elements in the third period and some of their compounds.

Table
(a)
(i)

On the axes, sketch the trend in melting point of the elements Na to S .

Question image
[ 1 ]
(ii)

Give three statements to explain your sketch.

1
2
3

[ 3 ]
(a)

Period 3 elements and their compounds show trends in their physical properties.

[ 3 ]
(i)

On Fig. 2.1 sketch a graph to show the melting points of the first five elements in Period 3.

Fig. 2.1

Fig. 2.1

[ 3 ]
[Maximum number: 1]

When copper is added to a solution of silver ions, the following equilibrium is established.

Cu( s)+2Ag+(aq)⇌Cu2+(aq)+2Ag( s)Kc=1.0×105\mathrm{Cu}(\mathrm{~s})+2 \mathrm{Ag}^{+}(\mathrm{aq}) \rightleftharpoons \mathrm{Cu}^{2+}(\mathrm{aq})+2 \mathrm{Ag}(\mathrm{~s}) \quad K_{\mathrm{c}}=1.0 \times 10^{5}

What is the concentration of silver ions at equilibrium when [Cu2+]=0.10 moldm−3\left[\mathrm{Cu}^{2+}\right]=0.10 \mathrm{~mol} \mathrm{dm}^{-3} ?

A

5.0×10−7 moldm−35.0 \times 10^{-7} \mathrm{~mol} \mathrm{dm}^{-3}

B

5.0×10−4 moldm−35.0 \times 10^{-4} \mathrm{~mol} \mathrm{dm}^{-3}

C

1.0×10−3 moldm−31.0 \times 10^{-3} \mathrm{~mol} \mathrm{dm}^{-3}

D

1.0×102 moldm−31.0 \times 10^{2} \mathrm{~mol} \mathrm{dm}^{-3}

[Maximum number: 1]

The elements Cl, Mg, Si and S are all in Period 3.
What is the correct sequence of the melting points of these elements, from lowest to highest?

Question image
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