9. The Periodic Table: chemical periodicity
A section of Chemistry, 9701
Listing 10 of 288 questions
State the relationship between the Faraday constant, F, the charge on the electron, e, and the Avogadro number, L. If the charge on the electron, the Ar and the valency of copper are known, the value of the Avogadro number can be determined experimentally. This is done by passing a known current for a known time through a copper electrolysis cell, and weighing the mass of copper deposited onto the cathode. Draw a diagram of suitable apparatus for carrying out this experiment. Label the following: power supply (with + and – terminals); anode; cathode; and ammeter. State the composition of the electrolyte. The following are the results obtained from one such experiment. current passed through the cell = 0.500 A time current was passed through cell = 30.0 min initial mass of copper cathode = 52.243 g final mass of copper cathode = 52.542 g Use these data and relevant information from the Data Booklet to calculate a value of L to 3 significant figures. L = Use relevant information from the Data Booklet to identify the substances formed at the anode and at the cathode when aqueous solutions of the following compounds are electrolysed. compound product at anode product at cathode AgF FeSO4 MgBr2
9701_s11_qp_43
THEORY
2011
Paper 4, Variant 3
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The ions of transition elements form complexes by reacting with ligands. State what is meant by the terms: complex, ligand. Two of the complexes formed by copper are [Cu(H2O)6]2+ and CuCl 4 2–. Draw three-dimensional diagrams of their structures in the boxes and name their shapes. [Cu(H2O)6]2+ shape: CuCl 4 2– shape: Platinum forms square-planar complexes, in which all four ligands lie in the same plane as the Pt atom. There are two isomeric complexes with the formula Pt(NH3)2Cl 2. Suggest the structures of the two isomers, and, by comparison with a similar type of isomerism in organic chemistry, suggest the type of isomerism shown here. Structures of isomers: isomer 1 isomer 2 Type of isomerism: Copper forms two series of compounds, one containing copper(ions and the other containing copper(ions. Complete the electronic structures of these ions. Cu( Cu( Use these electronic structures to explain why copper(salts are usually coloured, copper(salts are usually white or colourless. Copper(oxide and copper(oxide can both be used in the ceramic industry to give blue, green or red tints to glasses, glazes and enamels. The table lists the values for some compounds. compound / kJ mol–1 Cu2O–168.6 CuO–157.3 Cu(NO3)2–302.9 NO2+33.2 Copper(oxide can be produced in a pure form by heating copper(nitrate. Use suitable values from the table to calculate the H o for this reaction. Cu(NO3)2 CuO+ 2NO2+ 2 1 O2H o = kJ mol–1 Copper(oxide can be produced from copper(oxide. ● Use suitable values from the table to calculate H o for the reaction. 2CuOCu2O+ 2 1 O2H o = kJ mol–1 ● Hence suggest whether a low or a high temperature of oxidation would favour the production of copper(oxide. Explain your reasoning.
9701_s14_qp_41
THEORY
2014
Paper 4, Variant 1
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The ions of transition elements form complexes by reacting with ligands. State what is meant by the terms: complex, ligand. Two of the complexes formed by copper are [Cu(H2O)6]2+ and CuCl 4 2–. Draw three-dimensional diagrams of their structures in the boxes and name their shapes. [Cu(H2O)6]2+ shape: CuCl 4 2– shape: Platinum forms square-planar complexes, in which all four ligands lie in the same plane as the Pt atom. There are two isomeric complexes with the formula Pt(NH3)2Cl 2. Suggest the structures of the two isomers, and, by comparison with a similar type of isomerism in organic chemistry, suggest the type of isomerism shown here. Structures of isomers: isomer 1 isomer 2 Type of isomerism: Copper forms two series of compounds, one containing copper(ions and the other containing copper(ions. Complete the electronic structures of these ions. Cu( Cu( Use these electronic structures to explain why copper(salts are usually coloured, copper(salts are usually white or colourless. Copper(oxide and copper(oxide can both be used in the ceramic industry to give blue, green or red tints to glasses, glazes and enamels. The table lists the values for some compounds. compound / kJ mol–1 Cu2O–168.6 CuO–157.3 Cu(NO3)2–302.9 NO2+33.2 Copper(oxide can be produced in a pure form by heating copper(nitrate. Use suitable values from the table to calculate the H o for this reaction. Cu(NO3)2 CuO+ 2NO2+ 2 1 O2H o = kJ mol–1 Copper(oxide can be produced from copper(oxide. ● Use suitable values from the table to calculate H o for the reaction. 2CuOCu2O+ 2 1 O2H o = kJ mol–1 ● Hence suggest whether a low or a high temperature of oxidation would favour the production of copper(oxide. Explain your reasoning.
9701_s14_qp_43
THEORY
2014
Paper 4, Variant 3
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L and M are elements in Period 3 of the Periodic Table. Neither element is argon. Information about the Pauling electronegativity values of L and M is given. Pauling electronegativity value element the highest of the seven elements Na to Cl the lowest of the seven elements Na to Cl L M Three statements about elements L and M are given. Element L contains covalent bonds. Element L has a higher atomic number than element M. A compound of L and M contains ionic bonds. Which statements are correct?
9701_s23_qp_13
MCQ
2023
Paper 1, Variant 3
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The elements of the third period of the Periodic Table form chlorides of general formula ECl x where E represents the element. These chlorides show a variation in oxidation number from sodium to sulfur. Use the information given to complete the table below. formula of chloride NaCl MgCl 2 Al Cl 3 SiCl 4 PCl 3 SCl 2 oxidation number of element in the chloride By considering the electron configurations of the elements, explain the variation in oxidation number in the chlorides from Na to Al and from Si to S. Na to Al Si to S Sodium hydride, NaH, is a colourless crystalline solid which melts at 800 °C and has the same crystal structure as sodium chloride which has a melting point of 808 °C. When molten sodium chloride is electrolysed using graphite electrodes, a shiny deposit, D, forms on the cathode and a greenish-yellow gas is evolved from the anode. When molten sodium hydride is electrolysed, under suitable conditions using graphite electrodes, the same shiny deposit D is formed on the cathode and a colourless gas, G, is evolved from the anode. Describe with the aid of a diagram the bonding in a sodium chloride crystal. Suggest the type of bonding that is present in sodium hydride. What is the oxidation number of hydrogen in sodium hydride? Draw a ‘dot-and-cross’ diagram for sodium hydride. Show outer electrons only. The metals magnesium and aluminium form hydrides with formulae MgH2 and Al H3. The non-metals phosphorus and sulfur form hydrides with formulae PH3 and H2S. By considering their positions in the Periodic Table, suggest oxidation numbers for these four elements in their hydrides. compound MgH2 Al H3 PH3 H2S oxidation number of element in the hydride At room temperature, the chlorides of sodium, magnesium and aluminium are all solids which dissolve in water. The hydrides of sodium, magnesium and aluminium are also solids which react with water with the rapid evolution of the same colourless gas G in each case. What is the pH of the solutions formed when separate samples of sodium chloride, magnesium chloride, and aluminium chloride are dissolved in water? chloride sodium magnesium aluminium pH Suggest an equation for the reaction between sodium hydride and water. Suggest a value for the pH of the solution formed in . At room temperature, the chlorides of silicon, phosphorus and sulfur are all low melting point solids or low boiling point liquids that can be seen to react with water. Suggest what type of bonding is present in sulfur dichloride, SCl 2. Write a balanced equation for the reaction between the chloride of silicon, SiCl 4, and water.
9701_w09_qp_22
THEORY
2009
Paper 2, Variant 2
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