4. What was the experimental basis for determining that the nucleus occupies a very small fraction of the volume of an atom? A) Neutral particles are emitted when a sheet of beryllium is bombarded with α particles. B) Photographic plates exposed to uranium will darken. C) A cathode ray is attracted to a positivelycharged plate. D) A majority of α particles will pass through a thin metal sheet undeflected, while a small percentage scatter wildly.
7. Why does knowledge of atomic number enable us to deduce the number of electrons present in an atom? 8. Why do all atoms of an element have the same atomic number, although they may have different mass numbers? A) All atoms of an element have the same number of neutrons, but may have different numbers of protons. B) All atoms of an element have the same number of protons, but may have different numbers of neutrons. C) The sum of neutrons and protons is the same for every atom of an element. D) The sum of neutrons and electrons is the same for every atom of an element.
9. What do we call atoms of the same elements with different mass numbers? 10. What is the mass number of an iron atom that has 28 neutrons? 11. Calculate the number of neutrons of 239 Pu. 18. Which of the following is a difference between metals and nonmetals?
21. Elements whose names end with ium are usually metals; sodium is one example. Identify a nonmetal whose name also ends with ium. 23. Group the following elements in pairs that you would expect to show similar chemical properties: K, F, P, Na, Cl, and N. A) K/N; F/Na; Cl/N B) K/Na; F/Cl; P/N C) K/F; P/Na; Cl/N D) K/P; F/Na; Cl/N
24. What is the difference between an atom and a molecule? A) A molecule has more electrons than an atom. B) An atom is charged while a molecule is not. C) A molecule is an aggregate of atoms, while an atom, by definition, is a single particle. D) A molecule is bigger than an atom. 25. How are allotropes different from isotopes? 26. NH + 4 is an example of which of the following? A) a monatomic cation B) a monatomic anion C) a polyatomic cation D) a polyatomic anion
27. Which of the following is an element? A) N 2 B) NH 3 C) NO D) CO 28. Which of the following is a compound? A) N 2 B) H 2 C) O 3 D) SO 2
29. Which of the following describes the molecule SO 2? A) A diatomic molecule containing atoms of the same element. B) A diatomic molecule containing atoms of different elements. C) A polyatomic molecule containing atoms of the same element. 31. What is the number of protons and electrons in Na +? 32. What is the number of protons and electrons in S 2?
33. What is the number of protons and electrons in Mg 2+? 35. Which of the following molecules contains two elements in a ratio of 2:1? A) NO B) NCl 3 C) N 2 O 4 D) P 4 O 6
36. Which compound has the same empirical formula as C 6 H 12 O 6? A) C 12 H 24 O 12 B) C 3 H 3 O 3 C) CH 2 ON D) CHO 2 38. What is the empirical formula of C 6 H 6? 39. What is the empirical formula of P 4 O 10? 40. What is the empirical formula of N 2 O 5?
41. What is the empirical formula of Na 2 S 2 O 4? 42. What is the molecular formula of glycine, an amino acid present in proteins? H O H OH NH 2
44. Which of the following compounds is likely to be molecular? PbCl 2 LiF B 2 H 6 KCl 45. Which of the following compounds is likely to be ionic? CH 4 NaBr CCl 4 NF 3 46. Which of the following compounds is named potassium hydrogen phosphate? KH 2 PO 4 K 2 HPO 4 K 3 PO 4
47. Which of the following compounds is named lithium carbonate? Na 2 CO 3 LiHCO 3 LiCO Li 2 CO 3 48. What is the name of KMnO 4? 50. What is the formula for ammonium sulfate?
51. What is the formula for calcium hydrogen phosphate? 52. What is the formula for lead (II) carbonate? 53. What is the formula for copper (II) cyanide?
56. One isotope of a metallic element has mass number 65 and 35 neutrons in the nucleus. The cation derived from the isotope has 28 electrons. What is the symbol for this cation? A) Br B) Br 2+ C) Tb 2+ D) Zn 2+ Use the following to answer questions 58-61: ATOM OR ION OF ELEMENT A B C D E F G Number of electrons 5 10 18 28 36 5 9
Number of protons 5 7 19 30 35 5 9 Number of neutrons 5 7 20 36 46 6 10 58. Which of the species are neutral? 59. Which of the species are negatively charged? 60. Which of the species are positively charged? 62. What is wrong with or ambiguous about the phrase four molecules of NaCl?
63. Which of the following are elements? (a) SO 2, (b) S 8, (c) Cs, (d) N 2 O 5, (e) O, (f) O 2, (g) O 3, (h) CH 4, (i) KBr, (j) S, (k) P 4, (l) LiF 65. Why is magnesium chloride (MgCl2) not called magnesium(ii) chloride?
66. Some compounds are better known by their common names than by their systematic chemical names. What is the chemical formula of baking soda? 68. Which elements are most likely to form ionic compounds?
69. Which metallic elements are most likely to form cations with different charges? 78. The formula for calcium oxide is CaO. What are the formulas for magnesium oxide and strontium oxide? 83. Fluorine reacts with hydrogen (H) and deuterium (D) to form hydrogen fluoride (HF) and deuterium fluoride (DF), where deuterium is an isotope of hydrogen. If a given amount of fluorine reacts with one gram of hydrogen, with how much deuterium would the same amount of fluorine react?
85. Predict the formula of a binary compound formed from Sr and Cl. 87. Which of the following is an alkali metal whose cation contains 36 electrons?