OCR 2023 GCSE Combined Science B Twenty First Century Science J260/02: Chemistry (Foundation Tier) Question Paper & Mark Scheme (Merged)

2 © OCR 2023 1 The diagram shows part of Mendeleev’s Periodic Table. B 11 C 12 N 14 O 16 F 19 Al 27 Si 28 P 31 S 32 Cl 35.5 As 75 Se 79 Br 80 In 115 Sn 119 Sb 122 Te 128 I 127 (a) Give the symbols of the two elements shown in the diagram which are not in order of atomic mass. ........................................................... and ........................................................... [1] (b) Mendeleev left gaps for elements that had not been discovered. (i) Name the two elements that had not been discovered when Mendeleev wrote his Periodic Table. Use the diagram and the Data Sheet. ........................................................... and ........................................................... [2] (ii) Describe how the discovery of new elements supported Mendeleev’s decision to leave gaps. ........................................................................................................................................... ...................................................................................................................................... [1] 3 © OCR 2023 Turn over (c) The table shows the atomic number and electron arrangement of some of the elements in Group 1 of the modern Periodic Table. Element Atomic number Electron arrangement Lithium 3 2.1 Sodium 11 2.8.1 Potassium 19 2.8.8.1 Which two statements explain how the reactions of lithium, sodium and potassium are related to their electron arrangements and so to their atomic number? Tick () two boxes. The atomic number is the mass of the atom. The atomic number is the number of electrons in the atom. The atomic number is the number of neutrons in the atom. The elements all have the same electron a