Chemical Bonds and Electronegativity

CHEMICAL BONDS

• Definition: A chemical bond is a connection between two atoms that holds them together.

TYPES OF BONDS

• Ionic Bond:

  • Electrons are completely transferred from one atom (metal) to another (nonmetal).

  • Examples: Li & F, Na & Cl.

• Covalent Bond:

  • Electrons are shared between two nonmetal atoms.

  • Examples: C & O, H & H.

• Metallic Bond:

  • Electrons are shared between metal atoms.

  • Examples: Cu & Cu, Zn & Fe.

OCTET RULE

• States that atoms bond to achieve 8 electrons in their valence shell (exceptions: H & He with 2 electrons).

ELECTRONEGATIVITY

• Definition: The tendency of an atom to attract electrons towards itself.

• Polarity: Distribution of electrical charge.

POLAR COVALENT BOND

• Results when one atom is more electronegative than the other, leading to unequal sharing of electrons.

  • Electronegativity Difference (Diff): 0.5 - 1.7.

• Creates partial positive and negative charges.

NONPOLAR COVALENT BOND

• Both atoms are equally electronegative, leading to equal sharing of electrons.

  • Electronegativity Difference: 0 - 0.5.

IONIC BOND (continued)

• Involves complete transfer of electrons from a less electronegative atom (metal) to a more electronegative atom (nonmetal).

• Attraction between opposite charges holds atoms together.

• Electronegativity Diff for ionic bonds: 1.1