PRACTICE EXAM 3 ANSWER KEY

Transcription

1 PRACTICE EXAM 3 ANSWER KEY Part 3: Memorized Material I highly suggest that you bring pencil and big block eraser for Part 3 of the Exam. You may use your calculator for Part 3 of Exam 3. You may use the Periodic Table from Part 2. You may use the Polyatomic Ions Sheet from Part 2. You will not have access to model kits for Exam 3. Electronegativity Values will be given when they are needed. Timing Mastery = 25 min Competency = 40 min PART 3C TRUE/FALSE If the statement is True, write T in the first box. If the statement is False, write F in the first box. If the statement is False, find the word in the sentence that is underlined. Cross out the underlined word. In the box provided, write the word that will make the statement true. F 41) At room temperature, mercury is a monatomic solid. liquid F 42) At room temperature, the only element that is a diatomic solid is bromine. iodine T 43) Iron has two valence electrons. You don t have to show work, but Fe: 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 6 T 44) As you move from left to right on the periodic table, atomic radius increases. F 45) The AXE notation for a trigonal bipyramidal molecule is AX 4. tetrahedral T 46) The bond angle for a molecule for a bent molecule is <109.5 Page 1 of 6

2 Part 3D: Art/Diagrams Make sure to write lone pair electrons when they are present. Remember to write brackets when necessary. 47) Sketch the Lewis Dot Structure for the bromine atom. 48) Sketch the Lewis Dot Structure for the sodium atom. Na 49) Sketch the Lewis Dot Structure for C 3 6. You may not write cyclical structures. 50) Sketch the Lewis Dot Structure for carbon monoxide, CO. 51) Sketch the Lewis Dot Structure for the phosphonium ion: P 4 + P + Page 2 of 6

3 53) Answer the following questions about the diagram below: C C C O N GEOMETRY BOND ANGLES AXE NOTATION 53A) trigonal bipyramidal <109.5 AX 3 E 1 53B) tetrahedral AX 4 53C) bent <109.5 AX 2 E 2 *Clarification 53a) Assume that the nitrogen atom is the central atom. 53b) Assume that the carbon atom is the central atom. 53c) Assume that the oxygen atom is the central atom. Page 3 of 6

4 Information for Question 54 ELEMENT C O N F Cl Br I ELECTRONEGATIVITY VALUE ) For the following pairs of covalently bonded atoms: Write whether the covalent bond is polar or non-polar If the covalent bond is polar, indicate the polarity of each atom with + and notation. 54A) C non-polar (Electronegativity for Carbon) (Electronegativity for ydrogen) = = 0.4 Since the difference is in the 0 to 0.4 (inclusive) range, the bond is non-polar. Delta notation is not applied. + 54B) O polar (Electronegativity for oxygen) (Electronegativity for hydrogen) = = 1.4 Since the difference is between 0.4 and 1.7, the bond is polar. Since oxygen has the higher electonegativity value, it is slightly negative; hydrogen is slightly positive. 54C) C Br polar (Electronegativity for bromine) (Electronegativity for carbon) = = 0.3 Since the difference is below 0.4. The bond is non-polar. Delta notation is not applied. + 54D) I N polar (Electronegativity for nitrogen) (Electronegativity for iodine) = = 0.5 Since the difference is between 0.4 and 1.7, the bond is polar. Since nitrogen has the higher electonegativity value, it is slightly negative; iodine is slightly positive. 55) The bond below represents is polar covalent. Write the correct arrow notation to indicate the direction of polarity. F Cl Page 4 of 6

5 56) Rewrite the following elements in order of increasing atomic radius (smallest to largest). Si Mg F Cl F Cl Si Mg 57) Rewrite the following elements in order of increasing metallicity (less metallic to most metallic). Cs Fr Be Ba Be Ba Cs Fr 58) Define the term electronegativity. You do not need to supply any examples. Electronegativity is the tendency for an atom to attract the electron density in a covalent bond. 59A) Define the term isolelectronic. Isoelectronic means that two particles have the same electron configuration. 59B) Write the electron configuration for argon. Ar: 1s 2 2s 2 2p 6 3s 2 3p 6 59C) Write the electron configuration for the sulfide anion. S : 1s 2 2s 2 2p 6 3s 2 3p 4. Sulfur gains two electrons to become sulfide. So... S 2 : 1s 2 2s 2 2p 6 3s 2 3p 6 59D) Write the electron configuration for the sodium cation. Na : 1s 2 2s 2 2p 6 3s 1. Sodium loses one electron to become the sodium cation. So... Na + : 1s 2 2s 2 2p 6 59E) Are any of the particles in 59b, 59c, and 59d isoelectronic? If so, which ones? Yes, the sulfide anion and the argon atom are isoelectronic. Page 5 of 6

6 60) In an ionic compound, does aluminum need a Roman numeral to indicate its charge? Why or why not? 61) What is the charge of bismuth in Bi 2S 3? 3+ 62) What is the charge of iron in iron(iii) sulfate? 3+ 63) What is the charge of cobalt in CoS 3? 6+ 64) What is the charge of in manganese is Mn 2O 7? 7+ QUESTION 65 Question 65 will be a short essay question (five to eight sentences). The topic can be any one of the following: Explain why atomic radius decreases as you go from left to right on the periodic table. If you need two elements to use in your explanation, use the Bohr Models of oxygen and beryllium. Explain why ionization energy increases as you go from left to right on the periodic table. If you need two elements to use in your explanation, use the Bohr Models of oxygen and beryllium. Explain why ionization energy decreases as you move from the top of the periodic table (Period 1) to the bottom of the periodic table (Period 7). If you need two elements to use in your explanation, use the Borh Models of lithium and rubidium. This information is in your notes and in the text. You are finished with Part 3 of the Exam. If you do not wish to do the Extra Credit, turn in Part 3 and all of the reference tables. If you wish to do the Extra Credit, keep the reference tables, turn in Part 3, and ask for the Extra Credit. Page 6 of 6