Chemistry

1. HOMEWORKS 2010-13
Raymond Chang. Chemistry: McGraw Hill, tenth Edition, 2010.
HOMEWORK 3
Chapter 9
3.- Without referring to Figure 9.1, write Lewis dot symbols for atoms of the
following elements: (a) Be, (b) K, (c) Ca, (d) Ga, (e) O, (f) Br, (g) N, (h) I, (i) As,
(j)F.
17.- Use Lewis dot symbols to show the transfer of electrons between the
following atoms to forms cations and anions: (a) Na and F, (b) K and S, (c) Ba and
O, (d) Al and N.
29.- What is the diference between a Lewis dot symbol and a Lewis structure?
32.- Compare the properties of ionic compounds and covalent compounds.
36.- Arrange the following Bonds in order of increasing ionic carácter: carbon to
hydrogen, flourine to hydrogen, bromine to hydrogen, sodium to chlorine,
potasium to fluorine, lithium to chlorine.
39.- Classify the following bonds as ionic, polar, covalent, or covalent, and give
your rehaznos: (a) the CC bond in H3CCH3, (b) the KI bond in KI, (c) the NB bond
in H3NBCl3, (d) the CF bond in CF4.
45.- Write Lewis structures for the following molecules: (a)ICl, (b)PH3, (c)P4,
(each P is bonded to three other three atoms), (d) H2S, (e) N2H4, (f) HClO3, (g)
COBr2 (C is bonded to O and Br atoms)
Chapter 10
7.- Predict the geometries of the following species using the VSEPR method : (a)
PCl3, (b) CHCl3, (c) SiH4, (d)TeCl4.
18.- The bonds in beryllium hydride (BeH2) molecules are polar, and yet the
dipole momento of the molecule is zero. Explain.
22.- Does the molecule OCS have a higher or lower dipole moment than CS2?
Chapter 11
7.- The compounds Br2 and ICl have the same number of electrons, yet Br2 melts
at -7.2 oC and ICl melts at 27.2 oC. Explain.
17.- Explain in terms of intermolecular forces why (a) NH3 has a higher Bowling
point than CH4 and (b) KCl has a higher melting point than I2.

2. 18.- What kind of attractive forces must be overcome in order to (a)20 melt ice,
(b) boil molecular bromine, (c) melt solid iodine, and (d) disociate F2 into F
atoms?