Chemistry Lecture: Lewis Structures, Covalent Bonding, and Polyatomic Ions

Vocabulary flashcards covering Lewis structure conventions, bonding electron counts, resonance concepts, bond strength/length trends, and oxyanion formation based on the lecture.

Terminal Atoms

Atoms located on the outer edge of a molecule (such as hydrogen or halogens) that usually complete their octet or duet before remaining valence electrons are shared toward the center.

Central Atom

The atom placed in the middle of a molecular structure, typically chosen because it requires the greatest number of connections or is the most electropositive.

Carbon Disulfide ($CS_2$)

A chemical compound that forms the exact same double-bonded Lewis structure as carbon dioxide ($CO_2$) because sulfur sits in the same periodic column as oxygen and has $6$ valence electrons.

Ammonium ($NH_4^+$)

A positively charged polyatomic ion formed when a proton ($H^+$) attaches to the lone pair of an ammonia ($NH_3$) molecule, with the positive charge distributed equally across all four hydrogen atoms.

Cyanide Anion ($CN^-$)

A polyatomic anion with $10$ valence electrons featuring a carbon-nitrogen triple bond and a negative charge, sharing an identical electron configuration with dinitrogen ($N_2$).

Carbonate ($CO_3^{2-}$)

A stable polyatomic oxoanion with $24$ valence electrons that demonstrates electron delocalization, resulting in bond strengths intermediate between single and double bonds (approximately $1\frac{1}{3}$ bonds).

Resonance

A term describing molecules with delocalized electrons shared across multiple bonds; despite misleading double-headed arrow representations, the molecule exists as a single steady combination structure rather than oscillating back and forth.

Delocalization

The distribution of bonding electrons across three or more atoms within a molecule or polyatomic ion, producing intermediate bond orders rather than fixed, localized single or double bonds.

Dinitrogen ($N_2$)

A diatomic molecule with $10$ total valence electrons containing a triple bond between two nitrogen atoms, characterized as having the second strongest bond in the universe.

Carbon Monoxide ($CO$)

A diatomic molecule with $10$ total valence electrons featuring a triple bond between carbon and oxygen, characterized as having the single strongest bond in the universe.

Bond Length Trend

The relationship where an increased number of shared electron pairs (triple bonds compared to double or single bonds) draws atoms closer together, producing shorter and stronger bonds.

Oxyanions

Polyatomic anions formed by attaching oxygen atoms onto the lone electron pairs of simple monatomic anions (such as attaching oxygen onto phosphide, sulfide, or chloride).