Atomic Structure and Isotopes: Questions and Answers - Prof. Simon Bott, Study notes of Chemistry

Download Atomic Structure and Isotopes: Questions and Answers - Prof. Simon Bott and more Study notes Chemistry in PDF only on Docsity! CHAPTER 2 - QUESTIONS History 1. Which assumptions of Dalton’s atomic theory had to be revised or discarded because of the existence of stable isotopes? (A) The ultimate particles of matter are the atoms of elements, which are indivisible and indestructible. (B) All the atoms of a given element are alike in all respects. (C) The atoms of different elements differ in one or more properties. (D) Compounds are formed by combination of different kinds of atoms. 2. When alpha particles were shot at a gold foil target, most of the particles were undeflected. This indicated to Rutherford that (A) the gold foil was continuous matter. (B) the mass of the gold atoms was spread out thinly. (C) the atoms of gold were mostly empty space. (D) the alpha particles had great penetrating power. (E) the alpha particles had charges opposite to those on the nuclei 3. The atomic nucleus was discovered experimentally by: (A) William Crookes using a cathode ray tube (B) Millikan using a cathode ray tube (C) J. J. Thomas using a beam of alpha particles (D) Ernest Rutherford using a beam of alpha particles (E) Ernest Rutherford using a cathode ray tube Percent by Mass 4. What is the percentage of nitrogen by mass in (NH4)3PO4? (A) 22.6% (B) 12.4% (C) 26.3% (D) 28.2% 5. The percent by mass of oxygen in Ca(NO3)2 is (A) 22.8% (B) 94.0% (C) 58.5% (D) 47.0% (E) 29.3% 6. Calcium carbonate is 40% calcium and 48% oxygen by mass. What mass of carbon is contained in 150 lb of calcium carbonate? (A) 12 g (B) 60 lb (C) 18 lb (D) 72 lb (E) 12 lb 7. Which of the following compounds has the largest percent nitrogen by mass? (A) N2H4 (B) NH3 (C) Li3N (D) NaN3 (E) Li2NH 1 Atomic Structure 8. The number of neutrons in the nucleus of a specific atom is equal to its (A) atomic mass. (B) mass number. (C) atomic number. (D) mass number - atomic number. 9. In all neutral atoms, there are equal numbers of (A) protons and neutrons. (C) neutrons and electrons. (B) positrons and electrons. (D) electrons and protons. 10. Which statement concerning the structure of the atom is correct? (A) Protons and neutrons have most of the mass and occupy most of the volume of the atom. (B) Electrons have most of the mass and occupy most of the volume of the atom. (C) Electrons have most of the mass but occupy very little of the volume of the atom. (D) Protons and neutrons have most of the mass but occupy very little of the volume of the atom. 11. Which statement is true? (A) The nucleus of an atom contains neutrons and electrons. (B) The atomic number of an element is the number of protons in one atom. (C) The mass number of an atom is the number of protons in the nucleus plus the number of electrons. (D) The number of electrons outside the nucleus is the same as the number of neutrons in the nucleus. (E) A Cl– ion is a chlorine atom that has lost one electron 12. An atom of strontium–90 (9038Sr) contains (A) 38 electrons, 38 protons, 52 neutrons. (B) 38 electrons, 38 protons, 90 neutrons. (C) 52 electrons, 52 protons, 38 neutrons. (D) 52 electrons, 38 protons, 38 neutrons. 13. How many protons are present in a 127I- ion? (A) 72 (B) 127 (C) 54 (D) 53 (E) 73 14. Consider the radioactive isotope bromine-80. Select the combination which lists, respectively, the correct atomic number, number of neutrons and mass number for it. (A) 45, 80, 35 (B) 80, 46, 35 (C) 35, 45, 80 (D) 35, 80, 45 (E) 35, 46, 81 15. The species 11H, 2 1H, and 3 1H represent three (A) allotropes. (B) isomers. (C) homologs. (D) isotopes. 16. Elemental tin has several isotopes. All of them have the same: (A) number of protons (B) total number of neutrons and protons (C) mass number (D) number of neutrons (E) total number of neutrons and electrons 2