Chemical Bonding
Chapter 12
Chemical bonds hold groups of atoms together to form molecules and ionic solids.
Bonds are classified as
Ionic: Formed when one or more electrons are transferred to form positive and negative ions
Covalent: Electrons are shared equally between identical atoms
Polar covalent bond: Unequal electron sharing between different atoms
Electronegativity is the relative ability of an atom to attract the electrons shared with another atom in a bond.
The difference in electronegativity of the atoms forming a bond determines the polarity of that bond.
In stable compounds, atoms tend to achieve the electron configuration of the nearest noble gas atom.
In ionic compounds,
Nonmetals tend to gain electrons to reach the electron configuration of the next noble gas atom.
Metals tend to lose electrons to reach the electron configuration of the previous noble gas atom.
Ions group together to form compounds that are electrically neutral.
In covalent compounds, nonmetals share electrons so that both atoms achieve noble gas configurations.
Lewis structures represent the valence electron arrangements of the atoms in a compound.
The rules for drawing Lewis structures recognize the importance of noble gas electron configurations.
Duet rule for hydrogen
Octet rule for most other atoms
Some molecules violate the octet rule for the component atoms.
Examples are BF3, NO2, and NO.