Zumdahl • DeCoste chemistry world of Chapter 12

Table 12.1

Figure 12.3: Electronegativity values for selected elements.

Figure 12.4: The three possible types of bonds.

• Covalent
• Polar covalent
• Ionic

Bond Polarity & Dipole Moments

• Dipole moment: property of a molecule whereby the charge distribution can be represented by a center of positive charge and a center of negative charge
• Represent with arrow pointing toward center of negative charge
• All diatomic polar molecules have a dipole moment
• Dipole moments strongly effect properties
• Polarity of water crucial to life
• Allow materials to dissolve in water (attract + & -)
• Water molecules attracted to each other (higher boiling point – keeps water in on Earth from evaporating)

Figure 12.5: Charge distribution in the water molecule.

Figure 12.5: Water molecule behaves as if it had a positive and negative end.

Figure 12.6: Polar water molecules are strongly attracted to positive ions by their negative ends.

Figure 12.6: Polar water molecules are strongly attracted to negative ions by their positive ends.

Electron Configurations of Ions

• Main group metals form ions by losing enough electrons to achieve the configuration of the previous noble gas (transition metals behavior is more complicated)
• Nonmetals form ions by gaining enough electrons to achieve the configuration of the next noble gas

Table 12.2

Table 12.3

Electron Configurations & Bonding

• Ionic compounds react to form binary compounds with the ions having electron configurations of noble gases
• When two nonmetals react to form a covalent bond, they share electrons in a way that completes the valence-electron configurations of both atoms (they attain noble gas configurations).

Figure 12.8: Ions as packed spheres.

• LiF is empirical or simplest formula for Lithium Fluoride
• Actual compound contains huge & = numbers of Li+ and F- ions packed together