Eduqas Chemistry for A Level Year 1 & AS: Student Bk

12 When an aqueous solution of calcium hydroxide is added to an aqueous solution of sodium carbonate a white precipitate of calcium carbonate is seen. Write the ionic equation for this reaction. Include the relevant state symbols in the equation. [1] 1.2 1 (a) Name the particles contained in atomic nuclei and give their relative masses and charges by completing the table. [2] Particle Relative mass Relative charge (b) An element, X, has an atomic number of 9 and forms an ion X − . State the number of protons and electrons in this ion. [1] (c) The symbols 35 17 Cl, 37 17 Cl and 39 19 K, represent chlorine atoms and potassium atoms respectively. Use these symbols to explain the meaning of the terms: (i) Atomic number [1] (ii) Isotope [1] (d) Sketch a diagram to show the shape of a p orbital. [1] (e) Show the electronic configuration of a potassium atom. [1] 2 (a) Atoms which have unstable nuclei are radioactive. All living organic matter contains carbon-14, which emits β -particles and has a half-life of 5730 years. (i) Explain what is meant by the term half-life of a radioactive isotope. [1] (ii) Give the symbol of the element produced by the radioactive decay of 14 C, showing both its mass and atomic numbers. [1] (iii) State what happens in the nucleus of an atom when a β -particle forms. [1] (iv) Calculate how long it will take a sample of 14 C of mass 8g to decay to 1g. [1] (b) Some information relating to three other radioisotopes is given in the table. Isotope Half-life Radioactive emission 60 Co 5 years γ 63 Ni 100 years β 66 Cu 30 seconds β Use all the information to suggest which radioisotope would be the most suitable for use in a gauge to measure the thickness of aluminium foil. Explain your reasoning. [2] 3 (a) Magnesium is best known for burning with a characteristic brilliant white light; however, in industry it is the third most commonly used structural metal. The metal itself was first produced by Sir Humphry Davy in 1808 using electrolysis of a mixture of magnesia and mercury oxide. Magnesium has three stable isotopes 24 Mg, 25 Mg and 26 Mg. (i) State the number of protons present in an atom of 24 Mg. [1] (ii) Deduce the number of neutrons present in an atom of 26 Mg. [1] (b) Magnesium also has a radioactive isotope 28 Mg which has a half-life of 21 hours. If you started with 2.0g, calculate the mass of 28 Mg remaining after 84 hours. [1] (c) Name one useful radioactive isotope and describe how it is used. [2] Exam practice questions 77