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Unformatted text preview: Chemistry 2311 Homework Problems‐ Chapter 1 Section I: Circle the number which corresponds to the answer to each of the following questions. There is only one correct answer for each question. (a) Between which of the following two atoms will an ionic bond be formed? (1) F and Cl (2) C and N (3) K and F (4) C and O (b) Between which of the following two atoms will a covalent bond be formed? (1) C and O (2) Li and F (3) Mg and Cl (4) K and Br (c) Which of the following bonds is the most polar? (1) C‐C (2) C‐Br (3) C‐Si (4) C‐Cl (d) Which of the following is an incorrect Lewis structure? (1) C O O
(2) HO COH O
(3) O N O H (4) (e) Which of the following statements is not true of resonance structures? (1) The positions of nuclei in resonance structures must be the same. (2) The placement of the pertinent electrons in resonance structures is different. (3) Each resonance structure represents a real molecule that can be isolated. (4) The actual molecule will be more stable than any single resonance structure. N N O (f) Which of the following molecules and ions has an atom with a formal charge of +2? O
(1) HO S OH O
(2) HO S
O OH (3) O S O -2 (4) S S S (g) What is the ground state electron configuration of atomic sulfur (atomic number = 16)? (1) 1s22s22p63s13p5 (2) 1s22s22p63s13p4 (3) 1s22s22p63s23p4 (4) 1s22s22p63s23p5 (h) What is the ground state electron configuration of sulfide ion (S‐2)? (1) 1s22s22p63s23p43d2 (2) 1s22s22p63s23p6 (3) 1s22s22p63s13p43d3 (4) 1s22s22p63s23p44s2 (i) Which atomic orbitals overlap to form the double bond of ethylene (CH2=CH2)? (1) sp2 + sp2 and p + p (2) s + s and p + p (3) sp2 + sp2 and s + s (4) sp + sp and p + p (j) Which of the following are not resonance structures? + (1) H3C _ N CH3 C H CH2 H3C N CH3 CH CH2 _ O
+ H C OH H C OH O
(3) OH OH H C O H C _ (4) _ Section II: Indicate True (T) or False (F) for each of the following statements. (a) Different compounds that have the same molecular formula but different structures are called isomers. (b) An ionic bond results from the sharing of electrons between two atoms. (c) Lithium is more electronegative than oxygen. (d) Lewis structures show the connections between atoms in a molecule or ion using only valence electrons. (e) The formal charge on nitrogen of nitrate anion (NO3‐) is ‐1. (f) An atomic orbital is a region of space where the probability of finding an electron is large. (g) An electron in the 2px orbital of nitrogen (atomic number = 9) is higher energy than an electron in a 2pz orbital. (h) When atomic orbitals combine to form molecular orbitals, the number of molecular orbitals that results always equals the number of atomic orbitals that combine. (i) An anti‐bonding molecular orbital is higher energy than a bonding molecular orbital. (j) The rotational energy barrier associated with a carbon‐carbon double bond is very small. (k) A carbon‐carbon triple bond is shorter than a carbon‐carbon single bond. (l) The shape of the ammonia molecule (NH3) is pyramidal. Section III. Write or draw the answer(s) for each of the following questions in the space provided: (a) Draw the Lewis structure for H3PO4 and indicatethe formal charge at each atom. O HO P O OH (b) Draw a resonance structure for the benzyl cation. +
CH2 (c) Draw the shape of a 2pz atomic orbital. (d) Draw the shape of an sp hybridized atomic orbital. (e) From the Valence Shell Electron Pair Repulsion (VSEPR) Model draw the shape of the trichloromethyl carbanion, :CCL3‐ (f) Draw a constitutional isomer of 2‐bromo‐cis‐2‐butene. H Br H3C CH3 (g) Draw a stereoisomer of 2‐bromo‐cis‐2‐butene. (h) There are seven constitutional isomers with the molecular formula C4H10O. There are four alcohols and three ethers. Draw the dash formula representations for the three ethers. (i) Write a condensed structural formula for the following compound. H H C C H C C H C C H C H Cl C C Cl H HH (j) Draw a bond‐line formula for the following condensed structural formula. CH3CH=CClCH(CH3)Cl H (k) Designate the hybridization for the atoms indicated by the arrows. ...
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