NJC 3 Atomic structure tutorial ans 2023

National Junior College SH1 H2 Chemistry 1 Tutorial – Atomic Structure Discussion Questions Atomic Number and Mass Number 1. Use of the Data Booklet is relevant to this question. Nuclear magnetic resonance (NMR) spectroscopy is an analytical technique that uses the magnetic properties of certain atomic nuclei in order to elucidate the structure of an organic molecule. Atomic nuclei with an even number of protons and an odd number of neutrons (or vice versa) are most suitable for NMR spectroscopy. Which of the following nuclei is least suitable for NMR spectroscopy? A 28Si B 31P C 103Rh D 19F A: no. of protons 14, no. of neutrons = 28 – 14 = 14 (even no. protons and neutrons) B: no. of protons 15, no. of neutrons = 31 – 15 = 16 C: no. of protons 45, no. of neutrons = 103 – 45 = 58 D: no. of protons 9, no. of neutrons = 19 – 9 = 10 A 2 Use of the Data Booklet is relevant to this question. Tritium, 3 1 H, a radioactive isotope of hydrogen, slowly turns into a helium isotope 3 2 He. Which statements about the two isotopes are incorrect? 1 Both isotopes have more neutrons than electrons. 2 Both isotopes have the same number of protons in their nuclei. 3 Both isotopes have the same number of charged sub–atomic particles. A 2 only B 1 and 3 only C 2 and 3 only D 1, 2 and 3 H3 1 contains 1 proton, 1 electron and 2 (3 – 1) neutrons. He3 2 contains 2 protons, 2 electrons and 1 (3 – 2) neutron. 1 3He has less neutrons than electrons. 2 3H has one proton while 3He has two protons. They are isotopes of different element, hence they CANNOT have the same number of protons. 3 3H has two charged sub–atomic particles while 3He has four charged sub– atomic particles. D

National Junior College SH1 H2 Chemistry 2 3 Some isotopes are unstable and undergo nuclear (radioactive) reactions. In one type of reaction, an unstable nucleus assimilates an electron from an inner orbital of its electron cloud. The net effect is the conversion of a proton and an electron into a neutron. Which of the following describes this type of reaction? A 11C → 12C B 111I → 111Te C 76Br → 75Br D 76Kr → 75Br The conversion results in the loss of a proton. So proton no decrease by 1. The reactant and the product cannot be the same element. Therefore options A and C are NOT the answers. Since the proton is converted into a neutron, mass no (nucleon no do not change) B 2015 P3 Q5 5 Lithium metal and its compounds have many uses, ranging from nuclear chemistry, rechargeable batteries, organic reagents and pharmaceuticals. (a) Naturally occurring lithium contains isotopes 6Li and 7Li. (i) What is meant by the terms • proton number, • nucleon number? [1] proton number: number of protons in the nucleus of an atom nucleon number: t