9. The Periodic Table: chemical periodicity
A section of Chemistry, 9701
Listing 10 of 288 questions
Elements in the same period of the Periodic Table show trends in physical and chemical properties. The grids on this page and on the opposite page refer to the elements of the third period, Na to Cl. On each of these grids, draw a clear sketch to show the variation of the stated property. Below each grid, briefly explain the variation you have described in your sketch. For each explanation you should refer to the important factors that cause the differences in the property you are describing. Na Mg Al Si P S Cl atomic radius of element explanation Na Mg Al Si P S Cl melting point of element explanation Na Mg Al Si P S Cl electrical conductivity of element explanation The melting points of some of the oxides of the elements sodium to sulfur are given in the table below. compound Na2O MgO Al 2O3 SiO2 P4O6 SO2 mp / K What type of bond is broken when each of the following compounds is melted? Na2O SiO2 P4O6 Identify one of these six oxides that has no reaction at all with water.
9701_s11_qp_23
THEORY
2011
Paper 2, Variant 3
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On the following grids, plot points showing the variation in the named property of the Group IV elements. Your points should show for each element, whether the melting point/electrical conductivity is ‘high’, ‘medium’ or ‘low’. The point for silicon has already been plotted in each case. high medium melting point low C Si Ge Sn Pb high medium electrical conductivity low C Si Ge Sn Pb Suggest explanations of these trends in terms of the structure and bonding of the Group IV elements. melting point electrical conductivity Choose one reaction to illustrate each of the following statements. Write an equation for each of your chosen reactions, and describe what you would see as the reaction is carried out. PbO is more stable than PbO2. CO is easily oxidised to CO2. Aqueous SnCl2 is a useful reducing agent.
9701_s11_qp_42
THEORY
2011
Paper 4, Variant 2
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On the following grids, plot points showing the variation in the named property of the Group IV elements. Your points should show for each element, whether the melting point/electrical conductivity is ‘high’, ‘medium’ or ‘low’. The point for silicon has already been plotted in each case. high medium melting point low C Si Ge Sn Pb high medium electrical conductivity low C Si Ge Sn Pb Suggest explanations of these trends in terms of the structure and bonding of the Group IV elements. melting point electrical conductivity Choose one reaction to illustrate each of the following statements. Write an equation for each of your chosen reactions, and describe what you would see as the reaction is carried out. PbO is more stable than PbO2. CO is easily oxidised to CO2. Aqueous SnCl2 is a useful reducing agent.
9701_s11_qp_43
THEORY
2011
Paper 4, Variant 3
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Although the actual size of an atom cannot be measured exactly, it is possible to measure the distance between the nuclei of two atoms. For example, the ‘covalent radius’ of the Cl atom is assumed to be half of the distance between the nuclei in a Cl 2 molecule. Similarly, the ‘metallic radius’ is half of the distance between two metal atoms in the crystal lattice of a metal. These two types of radius are generally known as ‘atomic radii’. The table below contains the resulting atomic radii for the elements of period three of the Periodic Table, Na to Cl. element Na Mg Al Si P S Cl atomic radius / nm 0.186 0.160 0.143 0.117 0.110 0.104 0.099 Explain qualitatively this variation in atomic radius. Suggest why it is not possible to use the same type of measurement for argon, Ar. Use the Data Booklet to complete the following table of radii of the cations and anions formed by some of the period three elements. radius of cation / nm radius of anion / nm Na+ Mg2+ Al 3+ P3– S2– Cl – Explain the differences in size between the cations and the corresponding atoms. Explain the differences in size between the anions and the corresponding atoms. Each of the elements Na to Cl forms at least one oxide. Na2O is an ionic oxide, SO2 is a covalent oxide. Both oxides react with water. Write an equation for the reaction of each of these oxides with water. Na2O SO2 What is the pH of the resulting solution in each case? Na2O SO2 Write an equation for the reaction that occurs between the products of your reactions in .
9701_s12_qp_23
THEORY
2012
Paper 2, Variant 3
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