Periodicity AS/A Level

The elements Cl, Mg, Si and S are all in Period 3.

What is the correct sequence of melting points of these elements, from lowest to highest?

• A

• B

• C

• D

The relative magnitude of the property X of five elements is shown. P, Q, R, S, and T are all in Period 3 and have consecutive atomic numbers.

Which option shows a correct pairing of property X and element R?

• electrical conductivity - Al

• electronegativity - Si

• melting point - Al

• 2nd ionisation energy - Si

Which graph correctly shows the relative melting points of the elements Mg, Al, Si, and P plotted against their relative first ionisation energies?

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Magnesium chloride, MgCl₂, and silicon tetrachloride, SiCl₄, are separately added to water.

What are the approximate pH values of the solutions formed?

• A

• B

• C

• D

The elements magnesium and sulfur each form doubly charged ions.

How do the atomic radii and ionic radii for these elements compare?

• A

• B

• C

• D

Which graph correctly shows the relative melting points of the elements Mg, Al, Si and P plotted against their relative electronegativities?

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The diagram shows the melting points of eight elements with consecutive atomic numbers.

Which element could be sodium?

• A

• B

• C

• D

Elements Y and Z are both in Period 3.

When the chloride of Y is added to water, it reacts and a solution of pH 2 is produced.

When the chloride of Z is added to water, it dissolves and a solution of pH 7 is produced.

Which statement explains these observations.

• Both chlorides hydrolyse in water.

• Y is magnesium and Z is sodium.

• Y is phosphorus and Z is aluminium.

• Y is silicon and Z is sodium.

The graph below shows the variation of the first ionisation energy with proton number for some elements. The letters used are not the usual symbols for the elements.

Which statement about the elements is correct?

• P and X are in the same period in the Periodic Table.

• The general increase from Q to X is due to increasing atomic radius.

• The small decrease from R to S is due to decreased shielding.

• The small decrease from U to V is due to repulsion between paired electrons.

Each pair below consist of a sample of two separate elements. Each element is in its standard state at room temperature and pressure.

Which pair of elements has chemical bonds of the same type between their atoms?

• aluminium and phosphorus

• chlorine and argon

• magnesium and silicon

• sulfur and chlorine