Summary of Ionic and Molecular Compounds

Ions: Transfer of Electrons

  • Atoms form positive ions by losing electrons and negative ions by gaining electrons.

  • Ionic bonds are formed by attractive forces between positive and negative ions.

Ionic and Covalent Bonds

  • Bonds form as atoms lose, gain, or share valence electrons to achieve an octet (8 electrons).

  • Ionic bonds: valence electrons are transferred from metal to nonmetal.

  • Covalent bonds: nonmetals share electrons for stability.

Formation of Ions

  • Metals lose valence electrons to form cations (positive ions) due to low ionization energy.

  • Nonmetals gain valence electrons to form anions (negative ions).

Ionic Compounds Characteristics

  • Composed of positive and negative ions.

  • High melting/boiling points; solid at room temperature.

  • Ionic formula: neutral charge with balance of positive and negative charges.

Writing Ionic Formulas

  • Charge balance utilized for formula writing (e.g., Na+1 with N3- gives Na3N).

  • Formula structure: metal symbol written first, followed by nonmetal symbol.

Naming Ionic Compounds

  • Metal name first, followed by nonmetal with -ide suffix.

  • For transition metals, use Roman numerals to indicate charge.

  • Examples: KI - Potassium Iodide; MgBr2 - Magnesium Bromide.

Polyatomic Ions

  • Group of atoms with an overall charge (e.g., NH4+, SO4^2-).

  • Named with the positive ion first, followed by the polyatomic name.

Molecular Compounds

  • Formed when nonmetals share electrons.

  • Covalent naming: first element by name, second with -ide and use prefixes for subscripts.

Lewis Structures

  • Represent molecules with valence electron arrangements.

  • Attempt completion of octets through shared electrons.

Electronegativity and Bond Polarity

  • Electronegativity: tendency to attract shared electrons.

  • Bond types:

    • Nonpolar covalent: equal sharing (0.0 to 0.4).

    • Polar covalent: unequal sharing (0.5 to 1.8).

    • Ionic: transfer of electrons (1.9+).

Shapes and Polarity of Molecules

  • VSEPR theory: electron groups determine molecular shape.

  • Types: linear, trigonal planar, bent, tetrahedral, trigonal pyramidal.

  • Polar molecules have uneven charge distribution.

Intermolecular Forces

  • Ionic bonds in ionic compounds.

  • Hydrogen bonds and dipole-dipole in polar compounds.

  • Dispersion forces in nonpolar compounds due to temporary dipoles.