Name: Score: 17 / 17 points (100%) Review Topic 4: Electron Configurations and Lewis Structures Multiple Choice Identify the choice that best completes the statement or answers the question. B 1. An element has an electron configuration of 1s 2 2s 2 2p 6 3s 2. Which of these will be in the same group as this element? a. 1s 2 2s 2 2p 6 c. 1s 2 2s 2 2p 6 3s 1 b. 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 d. 1s 2 2s 2 2p 6 3s 2 3p 6 Groups are the columns and this is the only on that ends with s 2 D 2. One indicator that electrons in atoms are limited to specific energy levels is that a. atoms move faster when heated b. the light given off by atoms is all at the same wavelength c. the Doppler effect shows a shift in wavelength for H atom light d. light emitted from excited atoms occurs only at specific wavelengths D 3. atoms move faster when heated true but doesn t indicate specific energy levels the light given off by atoms is all at the same wavelength every atom has its own wavelengths, not the same the Doppler effect shows a shift in wavelength for H atom light the Doppler effect deals with sound, not light light emitted from excited atoms occurs only at specific wavelengths this is the one and the reason we can conduct a flame test. ns 2 np 3 Which of these elements is found in a family with the above electron configuration? a. Al c. Si b. Sr d. Sb n is a random number, in this case it would represent 5. The important information is p 3, which means we are in group 15. A 4. The Lewis electron dot system represents electrons in the a. outer energy level c. middle level b. inner level d. core level ANSWER: A This is talking about Lewis Dot Formulas, which the dots represent valance file:///c:/users/joseph%20morris/desktop/sol%20review%20topics/review%20topic%204/review_topic_4_sg.htm 1/6
electrons or outer electrons D 5. The elements that are characterized by having only five electrons in the p sublevel belong to which family of elements? a. Transition c. Noble gas b. Alkali d. Halogens Transition These have incomplete d Alkali These have 1 in the s sublevel Noble gas These have 6 in the p sublevel Halogens These have 5 in the p sublevel C 6. If the above diagram were the correct representation for the Lewis structure of a molecule, then the X would be representative of the element a. oxygen c. nitrogen b. fluorine d. sulfur If you add up the total number of electrons, we are dealing with 10 electrons. [4 dots + 3 lines (x2 electrons)]. We have the same element twice so, 10/2 = 5 valence electrons, which leads to nitrogen. C 7. Which of these elements contains four valence electrons? a. Helium c. Carbon b. Beryllium d. Oxygen Helium 2 Beryllium 2 (Group 2) Carbon 4 (Group 14) Oxygen 6 (Group 16) C 8. Which of the following orbital diagrams is incorrect because it violates Hund s rule? file:///c:/users/joseph%20morris/desktop/sol%20review%20topics/review%20topic%204/review_topic_4_sg.htm 2/6
a. b. c. d. Hund s Rule spread them out before pairing them together. C 9. What is the correct Lewis dot structure for arsenic? a. c. b. d. D 10. What shape does the molecule BF 3 have? a. Bent c. Tetrahedral b. Linear d. Trigonal planar The B will be surrounded by three F s which would make it either trigonal file:///c:/users/joseph%20morris/desktop/sol%20review%20topics/review%20topic%204/review_topic_4_sg.htm 3/6
planar or trigonal pyramidal. Since trigonal pyramidal is not an answer, it has to be trigonal planar. D 11. Which of the following is the correct molecular shape of CH 4? a. Bent c. Pyramidal b. Linear d. Tetrahedral The C is surrounded by 4 hydrogens, which make it tetrahedral. B 12. With n representing the outermost energy level, the electron configuration for that level for elements in Group 14 is a. ns 2 np 1 c. ns 2 np 3 b. ns 2 np 2 d. ns 2 np 4 All Group 14 have 4 valance electrons, and the only one above with 4 is ns 2 np 2 B 13. What is the electron configuration of scandium (Sc) in Sc(NO 3 ) 3? a. 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 1 c. 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 b. 1s 2 2s 2 2p 6 3s 2 3p 6 d. 1s 2 2s 2 2p 6 3s 2 3p 6 3d 3 The first important thing to remember is it says Sc in this compound, which is an ionic compound. The you have to remember that Sc would form the cation (positive part) and according to the formula, it would be a +3. After that, you have to subtract three electrons from its electron configuration and have the same configuration as argon (and all noble gases end in p 3 ) C 14. How many electrons are needed to completely fill the orbitals from 1s to 4p? a. 7 c. 36 b. 18 d. 46 First you have to determine the electron filling order from the picture 1s2s2p3s3p4s3d4p file:///c:/users/joseph%20morris/desktop/sol%20review%20topics/review%20topic%204/review_topic_4_sg.htm 4/6
Then you have to remember that s gets 2 electrons (from 1 box), p gets 6 (from 3 boxes), d gets 10 (from 5 boxes) (and f would get 14 from 7 boxes) Replacing this into the information above results in: 2+2+6+2+6+2+10+6 = 36 B 15. How many valence electrons does a neutral atom of silicon have? a. 3 c. 5 b. 4 d. 6 Group 14 elements all have 4 valence electrons (remember, ignoring 1 in front of 14 gives you valance electrons for groups 13 18) A 16. Which structure represents a nonpolar molecule? a. c. b. d. ANSWER: A To be nonpolar, the molecule has to be symmetrical. The only symmetrical molecule is a. b is not symmetrical due to the alcohol group (OH) being different from the rest of the Hs c is not symmetrical due to the Cl being different from the Hs d is not symmetrical due to the O being different from the Hs Numeric Response file:///c:/users/joseph%20morris/desktop/sol%20review%20topics/review%20topic%204/review_topic_4_sg.htm 5/6
Directions: Type your answer in the box. Use + and for the electrical charge. 17. What is the oxidation number of an oxide ion? RESPONSE: 2 ANSWER: 2 or 2 (oxide is the ionic version of oxygen and group 16 on the periodic table form 2 ions due to the fact that this column has 6 valence electrons and need to gain 2 more electrons. Since electrons are negative, gaining two makes a negative 2 charge). file:///c:/users/joseph%20morris/desktop/sol%20review%20topics/review%20topic%204/review_topic_4_sg.htm 6/6