Bonding & Molecular Structure
Atoms become chemical structures when electron density, charge, and geometry lower the energy of the whole system. Bond models describe different scales, from shared density between nuclei to lattices, molecular shape, and forces between molecules.
A bond is a model of charge distribution and energy.
Keep the selected atoms, controls, visual response, and interpretation together. Change the model scale without pretending that a Lewis line, an ionic pair, a VSEPR shape, and a bulk material are the same object.
Treat a covalent bond as electron density distributed across more than one nucleus, with polarity shifting the distribution.
Shared electron density becomes a bond
Keep the selector, response, and interpretation together. Each scene asks a different structural question.
A bond is not a rigid stick. It is a lower-energy distribution of electron density. Increasing bond order adds density between nuclei, while electronegativity shifts that density toward one atom.
The useful model changes when the question changes.
No single sketch carries every fact about bonding. Use density for polarity, lattices for ionic solids, domain geometry for shape, and intermolecular networks for bulk properties.
Electron density
Where is negative charge distributed?Covalent and polar-covalent models describe a continuum of shared density rather than two unrelated bond categories.
focus modelElectrostatic structure
What arrangement best stabilizes separated charge?Ionic bonding is a collective lattice interaction. One cation-anion pair is a useful fragment, not the entire crystal.
focus modelGeometry
How do electron domains constrain molecular shape?VSEPR organizes domains by repulsion, then removes lone-pair positions when naming the visible molecular geometry.
focus modelCollective forces
How do molecular attractions become bulk properties?Dispersion, dipoles, and hydrogen bonding compete with thermal motion to influence boiling, solubility, viscosity, and phase.
focus modelExtended structures create properties no single bond possesses.
Materials may repeat ionic attractions, delocalize electrons through a metal, or connect covalent bonds into a network. The repeating structure determines conductivity, hardness, melting behavior, and mechanical response.
Ionic crystal
high melting point; brittle cleavage
Metallic solid
conductive; malleable; reflective
Network covalent
very hard; high thermal stability
Lewis structures are ledgers, not photographs.
A Lewis structure tracks valence electrons, formal charge, and connectivity. It usually does not show orbital phase, electron correlation, true charge density, resonance weighting, or the motion of nuclei.