Chapter 4. Chemical Bonding and Molecular Shape

Ionic bonds form by electron transfer between a metal and a nonmetal (NaCl). Ionic solids have high melting points and conduct electricity when molten or dissolved. Covalent bonds involve electron sharing between nonmetals. Metallic bonding features a “sea” of delocalized electrons [1][8].

Lewis structures. Count total valence electrons, connect atoms with single bonds, complete octets (hydrogen needs two), and use multiple bonds if needed. Formal charge = valence electrons − nonbonding electrons − ½(bonding electrons) [2].

VSEPR theory. Electron groups around a central atom repel one another and arrange to minimize repulsion:

Polarity. A bond is polar if the electronegativity difference is significant; a molecule is polar if bond dipoles do not cancel.

Intermolecular forces, from weakest to strongest: London dispersion, dipole–dipole, hydrogen bonding. They govern boiling points and solubility [2][3].

Review: Draw the Lewis structure of CO₃²⁻ and state its shape.