Chemistry: Types of Chemical Bonds and Lewis Structures

Ionic Bonds

Formed when a metal transfers electrons to a nonmetal, producing positive and negative ions.

Covalent Bonds

Formed when two nonmetals share electrons.

Polar Covalent Bonds

Electrons are shared unevenly due to electronegativity differences, creating partial positive and partial negative ends.

Nonpolar Covalent Bonds

Electrons are shared equally between atoms; usually occurs between identical atoms or atoms with very small electronegativity differences.

Metallic Bonds

Metal atoms share a pool ('sea') of delocalized electrons, giving metals their conductivity, luster, and malleability.

Bond Determination (Electronegativity Difference)

Bond type depends on electronegativity difference: <0.5 = nonpolar covalent, 0.5-1.7 = polar covalent, >1.7 = ionic.

Lewis Structures

Diagrams showing how atoms share electrons.

Octet Rule

Atoms generally want 8 electrons in their valence shell to achieve stability like noble gases.

Incomplete Octet Exception

Some atoms form stable compounds with fewer than 8 electrons. Common for B and Be.

Expanded Octet Exception

Atoms in period 3 or higher can hold more than 8 electrons due to available d-orbitals.

Odd-Electron Molecules (Radicals)

Molecules that contain an odd number of electrons cannot give every atom a full octet.

Formal Charge

Formal Charge = (valence electrons) - (nonbonding electrons) - (bonding electrons ÷ 2).

Resonance

Occurs when multiple valid Lewis structures can be drawn, resulting in delocalized electrons.

Ionic Bonds Characteristics

Strong attraction, high melting/boiling points, and conductive when molten or dissolved in water.

Covalent Bonds Characteristics

Can be single, double, or triple. Generally low melting points and poor electrical conductivity.

Polar Covalent Bonds Characteristics

Have unequal sharing, creating partial charges.

Nonpolar Covalent Bonds Characteristics

Share electrons equally.

Metallic Bonds Characteristics

Responsible for conductivity and malleability.