Upload
chris-foltz
View
5.568
Download
2
Tags:
Embed Size (px)
Citation preview
CHEMICAL BONDINGChapter 6.1
Objectives:1. Define chemical bond2. Explain why most atoms form
chemical bonds3. Describe ionic and covalent bonding4. Explain why most chemical bonding
is neither purely ionic nor purely covalent
5. Classify bonding type according to electronegativity differences
Chemical Bonding
In nature, most atoms are joined to others by chemical bonds
Types of Chemical Bonds
Ionic bonding – bonding resulting from electrical attraction between large numbers of cations and anions.
• Covalent bonding – bond resulting from the sharing of electron pairs between two atoms
Transfer of electrons
Why are most atoms chemically bonded to each other?
• As independent particles – high potential energy
• Nature – favors a minimized potential energy
• Most atoms are less stable by themselves than when they are combined
• By bonding, atoms decrease in potential energy, become more stable
Ionic Bond Examples
Covalent Bond Examples
Ionic or Covalent?
• Rarely purely ionic or purely covalent• Usually somewhere in between, depending on how strongly each atom attracts electrons. (Electronegativity)
• Determine by calculating difference in electronegativity
For example: Cs – 0.7 F – 4.0
So, 4.0 – 0.7 = 3.3 Use scale to determine
Difference in Electronegativity
1. If the electronegativity difference (usually called DEN) is less than 0.3, then the bond is nonpolar covalent.2. If the DEN is between 0.3 and 1.6, the bond is considered polar covalent3. If the DEN is greater than 1.7, then the bond is ionic.
Chart of polarities
Polarity
• Nonpolar-covalent bond : bonding electrons are shared equally by the atoms
• balanced distribution of electric charge
• Polar-covalent bond : bonding electrons are shared unequally by the atoms
• unbalanced distribution of electric charge
Examples of Polar and Nonpolar Covalent Bonds
Nonpolar
Polar
C - H
O - H
H - H
O - O