9.2. Periodicity of chemical properties of the elements in Period 3
A subsection of Chemistry, 9701, through 9. The Periodic Table: chemical periodicity
Listing 10 of 224 questions
The elements in the third period, and their compounds, show trends in their physical and chemical properties. A sketch graph of the first ionisation energies of five successive elements in the third period is shown. ionisation energy atomic number P S Al Mg Si Explain why there is a general increase in the first ionisation energy across the third period. Sketch, on the graph, the position of the ionisation energies of the two elements that come before Mg in this sequence. Explain, with reference to electron arrangements, the decreases in first ionisation energy between Mg and Al and between P and S. Mg and Al P and S The chlorides of the elements in the third period behave in different ways when added to water, depending on their structure and bonding. L and M are each a chloride of an element in Period3. A student investigated L and M and their results are given. L is a white crystalline solid with a melting point of 987 K. L dissolves in water to form an approximately neutral solution. Addition of NaOHto an aqueous solution of L produces a white precipitate. M is a liquid with a boiling point of 331 K. M is hydrolysed rapidly by cold water to form a strongly acidic solution, a white solid and white fumes. Identify L and M. Explain any properties and observations described. Give equations where appropriate. L is M is
9701_w17_qp_23
THEORY
2017
Paper 2, Variant 3
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The table gives some data for elements in the third period and some of their compounds. element Na Mg Al Si P S type of bonding metallic covalent covalent formula of oxide P4O10 SO2 formula of chloride NaCl MgCl 2 SCl 2 Complete the table to show the bonding in the elements, and the formulae of their oxides and chlorides. SCl 2 is formed in the following reaction. S2Cl 2+ Cl 22SCl 2ΔH = – 40.6 kJ mol–1 Complete the ‘dot-and-cross’ diagram to show the bonding in a molecule of SCl 2. Show outer electrons only.  Complete and fully label the reaction pathway diagram for the reaction between S2Cl 2 and Cl 2. Include labels for activation energy, Ea, and enthalpy change of the forward reaction, ΔH. energy progress of reaction S2Cl 2+ Cl 2 On the axes, sketch the trend in melting point of the elements Na to S. melting point of element Na Mg Al Si P S  Give three statements to explain your sketch.  Write an equation for the reaction of P4O10 with water. SO2 can be released into the atmosphere when fossil fuels containing sulfur are burnt. State and explain one environmental consequence of the release of SO2 into the atmosphere. The elements in the third period show a general increase in their first ionisation energies from left to right. Identify two pairs of successive elements in the third period that do not agree with this statement. For each pair, explain why the change in ionisation energy does not agree with this statement. Use of the Data Booklet may help you to answer this question. pair 1 explanation pair 2 explanation  
9701_w18_qp_22
THEORY
2018
Paper 2, Variant 2
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Complete the table to give details of the type of bonding and structure shown by some of the oxides of Period3 elements. Na2O MgO Al 2O3 SiO2 SO3 boiling point / °C nature of oxide basic basic amphoteric acidic acidic bonding structure  Explain why the boiling point of SiO2 is much higher than the boiling point of SO3. Al 2O3 is an amphoteric oxide. Explain what is meant by the term amphoteric. Use chemical equations to illustrate your answer. State what you would observe when a small sample of Na2O is placed in water. Selenium is a Group16 element which shows similar chemical reactions to sulfur. Selenium reacts with fluorine to form SeF6 molecules. Predict the shape of a molecule of SeF6. The most stable oxide of selenium is SeO2. Gaseous SeO2 reacts to form a solid polymer, as shown. In the reaction one Se=O is replaced by two Se–O to form a polymer. O O Se O O Se ΔH = –346 kJ mol–1 The bond enthalpy of Se=O is 514 kJ mol–1. Use these data to calculate the bond enthalpy, in kJ mol–1, of Se–O.  bond enthalpy of Se–O = kJ mol–1  SeO2 shows similar chemical reactions to SO2. Suggest an equation to show the reaction of SeO2 with aqueous sodium hydroxide, NaOH. 
9701_w19_qp_21
THEORY
2019
Paper 2, Variant 1
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Oxygen is the most abundant element in the Earth’s crust. It reacts with other elements to form stable compounds, ions and molecules. Complete the table to give the formulae and acid/base behaviour of some of the oxides of the Period3 elements. element sodium aluminium silicon phosphorus sulfur formula of oxide Na2O SO3 acid/base behaviour amphoteric  Group2 elements form stable hydroxides, with general formula M(OH)2, where M is the Group2 element. Beryllium hydroxide, Be(OH)2, is an amphoteric compound that shows similar chemical reactions to aluminium oxide. State the meaning of the term amphoteric. Write an ionic equation for the reaction of magnesium hydroxide, Mg(OH)2, with hydrochloricacid. Two methods of preparing strontium hydroxide are shown. strontium strontium hydroxide strontium oxide H2O reaction 1 H2O reaction 2 State one difference between the observations you would make for reaction 1 and reaction2. State how the solubility of the Group2 hydroxides changes down the group. Sodium peroxide, Na2O2, reacts with CO2. Na2O2+ CO2Na2CO3+ 2O2The partial pressure of CO2in a 0.500 dm3 sample of air is 5.37 kPa at 20 °C. Calculate the amount, in moles, of CO2present in the sample of air at 20 °C.  amount of CO2= mol Calculate the mass of Na2O2that would react fully with the amount of CO2calculated in .  mass of Na2O2= g The peroxide ion, O2 2–, has a single covalent bond between the two oxygen atoms. Each oxygen atom carries a negative charge. Draw a ‘dot-and-cross’ diagram for the peroxide ion. Show outer electrons only.  
9701_w19_qp_22
THEORY
2019
Paper 2, Variant 2
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Complete the table to give details of the type of bonding and structure shown by some of the oxides of Period3 elements. Na2O MgO Al 2O3 SiO2 SO3 boiling point / °C nature of oxide basic basic amphoteric acidic acidic bonding structure  Explain why the boiling point of SiO2 is much higher than the boiling point of SO3. Al 2O3 is an amphoteric oxide. Explain what is meant by the term amphoteric. Use chemical equations to illustrate your answer. State what you would observe when a small sample of Na2O is placed in water. Selenium is a Group16 element which shows similar chemical reactions to sulfur. Selenium reacts with fluorine to form SeF6 molecules. Predict the shape of a molecule of SeF6. The most stable oxide of selenium is SeO2. Gaseous SeO2 reacts to form a solid polymer, as shown. In the reaction one Se=O is replaced by two Se–O to form a polymer. O O Se O O Se ΔH = –346 kJ mol–1 The bond enthalpy of Se=O is 514 kJ mol–1. Use these data to calculate the bond enthalpy, in kJ mol–1, of Se–O.  bond enthalpy of Se–O = kJ mol–1  SeO2 shows similar chemical reactions to SO2. Suggest an equation to show the reaction of SeO2 with aqueous sodium hydroxide, NaOH. 
9701_w19_qp_23
THEORY
2019
Paper 2, Variant 3
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