8.3. Group VII properties
A subsection of Chemistry, 0620, through 8. The Periodic Table
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This question is about halogens and halogen compounds. Deduce the number of electrons, neutrons and protons in one atom of the isotope of chlorine shown. 37Cl number of electrons number of neutrons number of protons  State why chlorine is used in water treatment. Aqueous chlorine reacts with aqueous potassium iodide. Complete the chemical equation for this reaction. Cl 2 + KI → KCl + I2 Explain in terms of the reactivity of the halogens why aqueous iodine does not react with aqueous potassium chloride. The table shows some properties of four halogens. halogen melting point / °C boiling point / °C density of liquid at boiling point in g / cm3 fluorine –220 1.51 chlorine –101 –35 bromine –7 3.12 iodine 4.93 Complete the table by predicting: ● the boiling point of fluorine ● the density of liquid chlorine at its boiling point. Predict the physical state of chlorine at –105 °C. Give a reason for your answer. 
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THEORY
2022
Paper 3, Variant 1
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This question is about Group I and Group VII elements. Deduce the number of electrons, neutrons and protons in one atom of the isotope of potassium shown. 40K number of electrons number of neutrons number of protons  Complete the chemical equation for the reaction of potassium with water to form potassiumhydroxide and a gas which pops with a lighted splint. 2K + H2O → 2KOH +  The table shows some properties of four Group I elements. element melting point / °C boiling point / °C relative hardness lithium 5.0 sodium 0.7 potassium rubidium 0.2 Complete the table by predicting: ● the melting point of sodium ● the relative hardness of potassium. Predict the physical state of potassium at 100 °C. Give a reason for your answer. Aqueous bromine reacts with aqueous potassium iodide. Br2 + 2KI → 2KBr + I2 Explain how this equation shows that bromine is more reactive than iodine. State the colour of aqueous iodine. Bromine is a diatomic molecule. State the meaning of the term diatomic. Bromine liquid turns into a gas very easily at room temperature. Choose the word which best describes a substance that evaporates easily. Draw a circle around your chosen answer. conductor flammable malleable volatile 
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THEORY
2022
Paper 3, Variant 2
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The Periodic Table can be used to classify elements. GroupI elements react with cold water to form alkaline solutions. Place the GroupI elements caesium, lithium, potassium, rubidium and sodium in their order of reactivity with water. Put the most reactive element first. most reactive least reactive  Name the alkaline solution formed when caesium reacts with cold water. GroupI elements have lower melting points than transition elements. Describe one other difference in the physical properties of Group I elements and transition elements. GroupVII elements are known as the halogens. Astatine is below iodine in GroupVII. Predict the physical state of astatine at room temperature and pressure. Some GroupVII elements react with aqueous solutions containing halide ions. When aqueous chlorine is added to aqueous potassium bromide a reaction occurs. The ionic half-equations for the reaction are shown. Cl 2+ 2e– → 2Cl –2Br –→ Br2+ 2e– Describe the colour change of the solution. original colour of potassium bromide solution final colour of reaction mixture  Identify the species that is oxidised. Explain your decision. species oxidised explanation  Bromine monochloride, BrCl, is made by the reaction between bromine and chlorine. The chemical equation is shown. Br2+ Cl 2→ 2BrCl bond bond energy in kJ / mol Br–Br Cl –Cl Br–Cl Calculate the overall energy change for the reaction using bond energies. Use the following steps. ● Calculate the total amount of energy required to break the bonds in 1mole of Br2and 1mole of Cl 2.  kJ ● Calculate the total amount of energy released when the bonds in 2 moles of BrCl are formed.  kJ ● Calculate the overall energy change for the reaction.  kJ / mol  
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THEORY
2022
Paper 4, Variant 1
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The Periodic Table can be used to classify elements. The GroupI metals react with cold water. Transition elements do not react with cold water. Describe two other differences in the chemical properties between GroupI metals and transition elements.  Describe the observations when potassium is added to cold water. Write a balanced equation for the reaction. Include state symbols. observations equation  Transition elements are stronger than GroupI metals. Describe two other differences in the physical properties of GroupI metals and transition elements.  Some GroupVII elements react with aqueous solutions containing halide ions. When aqueous bromine is added to aqueous potassium iodide a reaction occurs. The ionic half-equations for the reaction are shown. Br2+ 2e– → 2Br –2I–→ I2+ 2e– Describe the colour change of the solution. original colour of potassium iodide solution final colour of reaction mixture  State the name of the general term given to the type of reaction in which electrons are transferred from one species to another. Identify the oxidising agent in this reaction. Give a reason for your answer. oxidising agent reason  Use the key to complete the table to show the results of adding aqueous halogens to aqueous solutions of halides. One has been completed for you. halides key ✓ = reaction ✗ = no reaction KCl KBrKIhalogens Cl 2Br2✓ I2 
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THEORY
2022
Paper 4, Variant 3
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Table2.1 shows some properties of the halogens. Table 2.1 halogen melting point in °C boiling point in °C density at room temperature and pressure in g / cm3 fluorine –220 –188 0.0016 chlorine –101 –35 0.0032 bromine +59 3.1 iodine +114 +184 Use the information in Table2.1 to predict: the melting point of bromine ��������������������������������������������������������������������������������������������������������������������������������������� the density of iodine at room temperature and pressure ��������������������������������������������������������������������������������������������������������������������������������������� the physical state of chlorine at –10 °C. Give a reason for your answer. physical state reason  The equation for the reaction of aqueous chlorine with aqueous potassiumiodide is shown. Cl 2 + 2KI → I2 + 2KCl Choose the word which best describes this type of chemical reaction. Draw a circle around your chosen answer. addition displacement neutralisation polymerisation Explain why aqueous iodine does not react with aqueous potassiumchloride. Complete the diagram in Fig.2.1 to show the electronic configuration of a chlorine atom. Cl  Describe a test for chlorine. test observations  
0620_s23_qp_31
THEORY
2023
Paper 3, Variant 1
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Table2.1 shows some properties of the halogens. Table 2.1 halogen melting point in °C boiling point in °C density at room temperature and pressure in g / cm3 fluorine –220 –188 chlorine –101 0.003 bromine –7 +59 3.12 iodine +114 +184 4.93 Use the information in Table2.1 to predict: the boiling point of chlorine ������������������������������������������������������������������������������������������� the density of fluorine at room temperature and pressure �������������������������������������������� the physical state of iodine at +100 °C. Give a reason for your answer. physical state reason  Aqueous chlorine reacts with aqueous sodium bromide. Complete the word equation for this reaction. chlorine + sodium bromide → +  State a test for sodium ions. test observations  
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THEORY
2023
Paper 3, Variant 3
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Fluorine, chlorine and bromine are in GroupVII of the Periodic Table. State the name given to GroupVII elements. Explain why GroupVII elements have similar chemical properties. Complete Table2.1 to show the colour and state at r.t.p. of some GroupVII elements. Table 2.1 element colour state at r.t.p. fluorine pale yellow chlorine bromine liquid  Bromine has two naturally occurring isotopes, 79Br and 81Br. State the term given to the numbers 79 and 81 in these isotopes of bromine. Complete Table2.2 to show the number of protons, neutrons and electrons in the atom and ion of bromine shown. Table 2.2 79Br 81Br – protons neutrons electrons  Table 2.3 shows the relative abundances of the two naturally occurring isotopes of bromine. Table 2.3 isotope 79Br 81Br relative abundance 55% 45% Calculate the relative atomic mass of bromine to one decimal place.  relative atomic mass = Chlorine displaces bromine from aqueous potassiumbromide but does not displace fluorine from aqueous sodiumfluoride. Write the symbol equation for the reaction between chlorine and aqueous potassium bromide. State why chlorine does not displace fluorine from aqueous sodiumfluoride. Aqueous silvernitrate is a colourless solution containing Ag+ions. Describe what is seen when aqueous silvernitrate is added to aqueous sodiumchloride. Write the ionic equation for the reaction between aqueous silver nitrate and aqueous sodiumchloride. Include state symbols. 
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THEORY
2023
Paper 4, Variant 2
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