8.1 Multiple-Choice and Bimodal Questions 1) There are __________ paired and __________ unpaired electrons in the Lewis symbol for a phosphorus atom. A) 4, 2 B) 2, 4 C) 2, 3 D) 4, 3 E) 0, 3 Answer: C Diff: 1 Page Ref: Sec. 8.1 2) In the Lewis symbol for a fluorine atom, there are __________ paired and __________ unpaired electrons. A) 4, 2 B) 4,1 C) 2, 5 D) 6, 1 E) 0, 5 Answer: D Diff: 1 Page Ref: Sec. 8.1 3) Based on the octet rule, magnesium most likely forms a __________ ion.
Identify the condensed formula of the following structure: A) (CH3)2CHCHClCH(CH3)2 B) CH3CH(CH3)CHClCH(CH3)2 Ans: C C) D) (CH3)2CHCHClC(CH3)3 (CH3)3CCHClCH(CH3)3 9. What is the chemical formula of the following carbon skeleton diagram? A) C8H14 Ans: C B) C8H16 C) C8H18 D) C8H20 10. How many hydrogen atoms are there on carbon atoms 1 and 2, respectively, in the structure below? A) 4, 1 B) 4, 0 Ans: D C) 3, 1 D) 3, 0 11.
6. Copper has two stable isotopes,[pic]and [pic], with masses of 62.939598 amu and 64.927793 amu, respectively. Calculate the percent abundances of these isotopes of copper. 7. Chromium has four naturally occurring isotopes: chromium – 50 (4.35% at 49.946 amu) chromium – 52 (83.79% at 51.941 amu) chromium – 53 (9.50% at 52.941 amu), and chromium – 54 (2.36% at 53.939 amu) Calculate the average atomic mass of
104 kJ/mol C. 52 kJ/mol D. -52 kJ/mol E. -104 kJ/mol 59. Give the number of lone pairs around the central atom and the molecular geometry of SCl2. A. 0 lone pairs, linear B. 1 lone pair, bent C. 2 lone pairs, bent D. 3 lone pairs, bent E. 3 lone pairs, linear 60.
Which pairs will react from an ionic compound? Chlorine and oxygen Nitrogen and Lithium b. Which pairs will react from a molecular compound? Flour nine and Argon c. Which pairs will not react to form a compound? Aluminium and potassium 7) A certain particle was found to contain sixteen protons and eighteen electrons.
Using the periodic table, determine the result of the following calculation: the number of electrons in the outer shell of a hydrogen atom minus the number of electrons in the outer shell of a helium atom plus the number of electrons in the outer shell of a hydrogen atom. • 8 electrons, minus 2 for the first orbital, second orbital will have 6 making them valence 5. When is an electron a valence electron? Why are valence electrons especially important in chemical reactions? • When it is on the very outside level away from the nucleus A valence electron is one that occupies the highest energy level for any electron in a particular neutral atom.
9) The ionic bond of sodium chloride is formed when A) chlorine gains an electron from sodium. B) sodium and chlorine share an electron pair. C) sodium and chlorine both lose electrons from their outer valence shells. D) sodium gains an electron from chlorine. E) chlorine gains a proton from sodium.
4 Calculate the molar mass of these compounds: (relative atomic masses: H = 1; N = 14; O = 16; S = 32; Cu = 64; Br = 80; Pb = 207) (a) copper nitrate, Ca(NO3)2 (b) lead bromate, Pb(BrO3)2 (c) ammonium sulfate, (NH4)2SO4 5 The equation for the complete combustion of methane is shown below. CH4 + 2O2 → CO2 + 2H2O When 80 g of methane is completely combusted, 220 g of carbon dioxide and 180 g of water are formed. (a) Why is the mass of carbon dioxide formed greater than the mass of methane burnt? (b) Calculate the mass of oxygen that reacted. (c) Calculate the mass of water formed when 20 g of methane undergoes complete combustion.