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Polarity of Bonds and Molecules Mrs. Huelin Chemistry April 24, 2012

Polarity of Bonds and Molecules

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Polarity of Bonds and Molecules. Mrs. Huelin Chemistry April 24, 2012. Polarity. of bonds … HCl H 2 O. of molecules … H 2 O CO 2. For each molecule, draw the Lewis structure, predict the shape and bond angle, and identify as polar or nonpolar . . Br 2 HCN C 2 H 2 NH 4 +. H 2 S - PowerPoint PPT Presentation

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Page 1: Polarity of Bonds and Molecules

Polarity of Bonds and Molecules

Mrs. Huelin ChemistryApril 24,

2012

Page 2: Polarity of Bonds and Molecules

Polarityof bonds …HCl

H2O

of molecules …H2O

CO2

Page 3: Polarity of Bonds and Molecules

For each molecule, draw the Lewis structure, predict the shape and bond angle, and identify as polar or nonpolar. Br2

HCN

C2H2

NH4+

H2S

PF3

CH2O

MgO

Page 4: Polarity of Bonds and Molecules

Electronegativity differences indicate Polarity

Page 5: Polarity of Bonds and Molecules

Electronegativity difference (∆En) and Bond type

Page 6: Polarity of Bonds and Molecules

For each pair of elements, calculate the electronegativity difference and label the bond type (polar covalent, nonpolar covalent, or ionic).H, ClH, SS, ClNa, FCl, BrAl, Br

Page 7: Polarity of Bonds and Molecules

Energy Practice ProblemGiven the following bond

dissociation energy values, calculate the total energy that would be required to break all of the covalent bonds in 0.25 mol of ethane (C2H6).

C-C = 347 kJ/molC-H = 393 kJ/mol

Page 8: Polarity of Bonds and Molecules

VIDEO LESSONWater, a polar molecule, on YouTube:

http://www.youtube.com/watch?v=DVCYlST6mYQ

Page 9: Polarity of Bonds and Molecules

REVIEWIonic and Covalent CompoundsPractice Quiz and Graphics:

http://www.elmhurst.edu/~chm/vchembook/145Areview.html

Page 10: Polarity of Bonds and Molecules

Internet resourcesMolecular polarity:

http://www.elmhurst.edu/~chm/vchembook/210polarity.html

Polar covalent compounds: http://www.elmhurst.edu/~chm/vchembook/152Apolar.html

Nonpolar covalent compounds: http://www.elmhurst.edu/~chm/vchembook/150Anpcovalent.html

Ionic compounds: http://www.elmhurst.edu/~chm/vchembook/143Aioniccpds.html

Compare Ionic, Polar, and Nonpolar Bonds: http://www.elmhurst.edu/~chm/vchembook/153Acompare.html

Page 11: Polarity of Bonds and Molecules

Properties of Covalent CompoundsLow melting and boiling points

(melting sugar, not salt)Many exist as gases or vaporize

readily at room temperature (oxygen, carbon dioxide)

Form relatively soft solids (paraffin wax)

Page 12: Polarity of Bonds and Molecules

Forces of Attraction Intramolecular

forces (bonding forces)

Covalent bond is strong (sharing of electrons)

Covalent network solids = brittle, nonconductors, extremely hard, very high melting point (diamond, quartz)

Intermolecular forces (a.k.a. van der Waals forces)Dispersion (induced dipole)

= between nonpolar molecules

Dipole-dipole = between polar molecules

Hydrogen bond = between hydrogen on one molecule and fluorine, oxygen, or nitrogen on another

Page 13: Polarity of Bonds and Molecules

Multiple Choice Review1. Which

substance contains both covalent and ionic bonds?

a) NH4NO3

b) CH3OCH3

c) LiFd) CaCl2

2. Which of

these bonds is most polar?

a) H-Clb) H-Brc) H-Fd) H-I

3. Which of these molecules can form a hydrogen bond with a water molecule?

a) N2

b) NH3

c) O2

d) CH4