Does so2 have polar bonds

(e) HzO and NH3 are polar molecules, but CHa is nonpolar.

(f) In methanol, CH3OH, the O-H bond is more polar than the C-O bond.

(g) Dichloromethane, CH.zCl2,is polar, but tetrachlo- romethane, CCla, is nonpolar.

(h) Ethanol, CHBCH2OH, the alcohol of alcoholic bev- erages, has polar bonds, has a net dipole, and is a polar mo1ecule.

Both CO2 and SO2 have polar bonds. Account for the fact that CO2 is nonpolar and SO2 is polar.

Consider the molecule boron trifluoride, BF3. (a) Write a Lewis structure for BF3. (b) Predict the F-B-F bond angles using the

VSEPR model. (c) Does BF3 have polar bonds? Is it a polar

molecule?

Is it possible for a molecule to have polar bonds and yet have no dipole? ExPlain.

Is it possible for a molecule to have no polar bonds and yet have a dipole? ExPlain.

In each case, tell whether the bond is ionic, polar co- valent, or nonpolar covalent. (a) Brz (b) BrCI (c) HCI (d) SrFz

3.90

- (e) SiHa (0 CO G) N, G) CsCl

3.91 Account for the fact that chloromethane, CH3CI, which has only one polar C-Cl bond, is a polar mol- ecule, but carbon tetrachloride, CCla, which has four polar C-Cl bonds, is a nonpolar molecule.

Chemical Csnnections 9.92 (Chemical Connections 3A) What are the three main

inorganic components of one dry mixture currently used to create sYnthetic bone?

3.93 (Chemical Connections 3B) Why is sodium iodide often present in the table salt we buy at the grocery store?

3.54 (Chemical Connections 38) What is a medical use of barium sulfate?

3.95 (Chemical Connections 38) What is a medical use of potassium permanganate?

3.96 (Chemical Connections 3A) What is the most preva- lent metal ion in bone and tooth enamel?

3.97 (Chemical Connections 3C) In what way does the gas nitric oxide, NO, contribute to the acidity of acid rain?

Additional Problems 3.98 Explain why argon does not form either (a) ionic

bonds or (b) covalent bonds.

3.99 Knowing what you do about covalent bonding in com- pounds of carbon, nitrogen, and oxygen and given the fact that silicon isjust below carbon in the Periodic Table, phosphorus is just below nitrogen, and sulfur

Problems td.=

is just below oxygen, predict the molecular formula for the compound formed by (a) silicon and chlorine' (b) phosphorus and hYdrogen, and (c) sulfur and hydrogen'

3.100 Use the valence-shell electron-pair repulsion model

to predict the shape of a molecule in which a cenhal atom is surrounded by frve regions of electron density-as, for example, in phosphorus pentaflue ride, PF5. (Hint: Use molecular models or if you do not have a set handy, use marshmallows or gum- drops and toothpicks.)

3.101 Use the valence-shell electron-pair repulsion model

to predict the shape of a molecule in which a central atom is surrounded by six regions ofelectron density, as, for example, in sulfur hexa-fluoride, SF6'

3.102 Chlorine dioxide, ClO2, is a yellow to reddish yellow gas at room temperature. This strong oxidizing agent is used for bleaching cellulose, paper pulp, and textiles and for water purifrcation. It was the gas used to kill anthrax spores in the anthrax- contaminated Hart Senate Office Building' (a) How many valence electrons are present

in ClO2? (b) Draw a Lewis structure for this molecule. (Hint:

The order of attachment of atoms in this molecule is O-CI-O. Chlorine is a third-period element, and its valence shell may contain more than eight electrons.)

3.103 Using the information in Figure 2.16, estimate the H-O and H-S distances (the atom-atom dis- tances) in H2O and H2S, respectively.

3.104 Arrange the single covalent bonds within each set in order of increasing PolaritY. (a) C-H, O-H, N-H (b) C-H, C-Cl, C-I (c) C-C, C-O, C-N

3.105 Consider the structure ofVitamin E shown below, which is found most abundantly in wheat germ orl sunflower, and safflower oils:

H.C"L Hz "-q'"--g-"-?', H2 ?t' Ez !:' Hz !:' ,""-i-a-'c-o-?-c-cic-cH-a-cic'cH-( -c- -cH-i H3C H2 H2 H2 H2 i' H, CE3HrC

Viramin tr

(a) Identify the various types ofgeometries present in each central atom usingVSEPR theory-

(b) Determine the various relative bond angles as- sociated with each central atom usingVSEPR theorY.

(c) Which is the most polar bond tu lifamin E? (d) Would you predict Vitamin E to be polar or

nonpolar?