chemistry/chemical_bonding/intro.md

Scope — Fundamental types of chemical bonds, simple models for bond formation, and core vocabulary contributors and learners should share.

Ionic bond — electrostatic attraction between oppositely charged ions formed by electron transfer.
Covalent bond — shared electron pairs between atoms; can be nonpolar or polar depending on electronegativity differences.
Metallic bond — delocalized electrons across a lattice of metal cations enabling conductivity and malleability.

Q: What determines whether a bond is ionic or covalent?
A: The difference in electronegativity between atoms; large differences favor ionic character, small differences favor covalent sharing.
Q: Why are ionic compounds often solid and brittle?
A: Strong lattice electrostatic forces hold ions in fixed positions; shifting layers brings like charges together and causes fracture.
Q: What is bond polarity and how is it measured qualitatively?
A: Polarity arises from unequal electron sharing; qualitatively assessed by electronegativity difference and dipole moment direction.

Classify a short list of compounds (NaCl, H₂O, CO₂, CH₄) as ionic, polar covalent, or nonpolar covalent and justify each choice.