CHEMISTRY MID-TERM STUDY GUIDE For questions 1-6, determine the number of significant figures in each measurement. _____1) 4658 g _____ 3) 0.0020 km _____5) 200 m _____2) 360.0 cm _____4) 7.02x105 mm _____6) 8050. S For questions 7-10, determine the number of significant figures in the calculated answers without solving the problems. _____7) 4.033 X 8.99 = _____9) 34.6 + 22.22 = _____8) 0.330 / 5.6 = _____10) 22899 – 2 = _____11) In the measurement 305.67g, which digit is estimated? a. The 3 b. The 0 c. The 6 d. The 7 _____12) A piece of paper measures 220.5 cm by 76.3 cm. What is the area of this piece of paper expressed to the correct number of sig. figs.? a. 16824.15 cm2 b. 16824 cm2 c. 16820 cm2 d. 16800 cm2 _____13) A sample of metal is found to have a density of 8.44 g/mL and a mass of 10.00g. What is the volume of this metal? a. 1.18 mL b. 1.180 mL c. 0.844 mL d. 0.84 mL _____14) Calculate the density of a gas that has a volume of 1.033x10-2 L and a mass of 4.22x10-4 g. a. 4.09x102 g/L b. 4.09x10-2 g/L c. 2.45x101 L/g For questions 15 – 18 choose “A” if the statement refers to an ionic compound and “B” if the statement refers to a covalent compound. _____15) Exist as neutral molecules. _____16) Made from a metallic and a nonmetallic element. _____17) Made from 2 or more nonmetallic elements. _____18) A crystal lattice structure with a very high melting point. _____19) How many dots does nitrogen have in its electron dot diagram? a. 2 b. 4 c. 5 d. 7 _____20) Which molecule’s central atom does not follow the octet rule? a. SF6 b. NO2 c. NH3 d. CBr4 _____21) Which of the following is a nonpolar molecule? a. HCN b. CBr4 c. NH3 d. H2O _____22) Which of the following elements exists as a diatomic molecule? a. Ba b. N c. Cl d. Ar _____23) All atoms of the same element have the same: a. number of protons b. number of neutrons c. mass number d. mass _____24) How do the isotopes hydrogen-2 and hydrogen-3 differ? a. hydrogen-3 has one more electron than hydrogen -2. c. hydrogen-2 has three protons. b. hydrogen-3 has two neutrons. d. hydrogen-2 has no protons. _____25) An atom of an element with atomic number 48 and mass number 120 contains a. 48 protons, 48 electrons, and 72 neutrons. c. 120 protons, 48 electrons, and 72 neutrons. b. 72 protons, 48 electrons, and 48 neutrons. d. 72 protons, 72 electrons, and 48 neutrons. _____26) Which symbol correctly represents an element(D) whose atoms contain 15 protons and 20 neutrons? a. 2015D b. 1520D c. 3515D d. 1535D _____27. The element argon contains the following isotopes with their relative abundance (RA) and mass: 36 Ar (RA 0.337%; mass 35.978 amu); 38Ar (RA 0.063%; mass 37.963 amu); 40Ar (RA 99.600%; mass 39.962 amu). Calculate the average atomic mass of argon. a. 37.967 amu b. 35.978 amu c. 38.000 amu d. 39.947 amu _____28) Which of the following statements is correct? a. Electrons are positively charged. c. Protons are negatively charged. b. Neutrons have no charge. d. Atoms are positively charged. _____29) Which of the following statements is not consistent with the results obtained in Rutherford’s gold foil experiment? a. The nucleus of an atom is positively charged. b. Atoms are composed mainly of empty space. c. The nucleus contains all of the mass of the atom. d. Electrons are contained in the nucleus of an atom. _____30. After 252 days, a 24 g sample of scandium-42 contains only 3.0 g of the isotope. What is the half-life of scandium? a. 84 days b. 10.5 days c. 31.5 days d. 126 days For questions 31 – 38, match the correct formula with the correct name. If a name given does not match a formula, place NA in the blank for not applicable. a. N2O5 b. KCl c. Pb(NO3)2 d. CO2 e. V2S5 _____31) Lead (II) nitrate _____32) dinitrogen pentoxide _____33) Lead nitrate _____34) potassium (I) chloride _____35) Potassium chloride _____36) carbon dioxide _____37) vanadium (II) sulfide _____38) vanadium (V) sulfide _____39) Which of the compounds listed below contains the Fe a. FeO b. FeF2 c. Fe2O3 3+ ion? d. FeSO4 _____40) Which statement best describes a group 2 element such as barium? a. Forms a cation by gaining 2 electrons. b. Forms an anion by losing 2 electrons. c. Forms a cation by losing 2 electrons. d. Forms an anion by gaining 2 electrons. For questions 41-44, match the correct formula with the correct name. a. HCl b. HClO c. HClO3 d. HClO2 _____41) chloric acid _____42) hydrochloric acid _____43) chlorous acid _____44) hypochlorous acid For questions 45 – 49 select: true (T) or false (F): _____45) In an electron configuration, sublevels are filled in order of increasing energy. _____46) The “p” orbitals are found in every energy level. _____47) The total number of electrons in a configuration can be determined by adding the superscripted numbers. _____48) The abbreviated electron configuration of osmium (Os) would start with [Kr]. _____49) The “d” orbitals can hold a maximum of 10 electrons. OPEN-ENDED SECTION: Please answer on a separate sheet of paper. 1. Draw a Lewis dot diagram for PCl3, identify its shape and molecular polarity. 2. Name the following compounds: CS2 and Sn(BrO3)2. Identify each as either ionic or molecular and explain, in detail, the differences in how each one is named. 3. Calculate the amount of energy needed to raise the temperature of 400.0 g of ice from -10.0OC to liquid water at 60.0 OC. (hint: use your energy graph for water to get all the constants you need) 4. Was the change in number 3 an endothermic or exothermic change?