Organic Chemistry Fundamentals: Carbon-Based Bonding and Isomerism

Vocabulary flashcards covering key concepts from the lecture notes on carbon-based chemistry, bonding, isomerism, and Lewis structures.

Organic chemistry

The study of carbon-based molecules and how they interact, including how bonds form and break and how reactions occur.

Constitutional isomer

Compounds with the same molecular formula but different connectivity (bonding patterns); different connectivity leads to different properties.

C2H6O constitutional isomers

Two isomers of the formula C2H6O: ethanol (CH3CH2OH) and dimethyl ether (CH3OCH3).

Ethanol

CH3CH2OH; one constitutional isomer of C2H6O.

Dimethyl ether

CH3OCH3; the other constitutional isomer of C2H6O.

Covalent bond

A bond formed by sharing electrons between two atoms, typically between nonmetals.

Nonpolar covalent bond

A covalent bond with negligible polarity; electrons are shared roughly equally (example: C–C bond).

Polar covalent bond

A covalent bond with unequal electron sharing due to differences in electronegativity, creating partial charges (δ+ and δ−).

Ionic bond

A bond formed between metals and nonmetals by transfer of electrons, resulting in oppositely charged ions; typically considered inorganic.

Electronegativity

The tendency of an atom to attract shared electrons; increases up and to the right on the periodic table (excluding noble gases); fluorine is the most electronegative.

Partial charge (δ+ and δ−)

Indicates uneven electron distribution in a polar bond; δ+ on the less electronegative atom, δ− on the more electronegative atom.

Ammonium

NH4+, a polyatomic cation often seen in ionic salts.

Cyanate

OCN−, a polyatomic anion often seen in ionic salts.

Valence electrons

The outer-shell electrons involved in bonding; typical counts: C 4, N 3, O 2, H and halogens 1; these patterns guide bonding in organic molecules.

Octet rule

Atoms tend to achieve eight electrons in their valence shell through bonding and lone pairs to reach a stable configuration.

Carbon four bonds

Carbon commonly forms four covalent bonds because it has four valence electrons and seeks four more to fulfill its octet.

Lewis structure

A drawing that shows bonds and lone pairs; guidelines include placing the least electronegative atom in the middle, aiming for symmetry, and using multiple bonds to satisfy octets.

Formal charge

A bookkeeping method to assign charges to atoms in a Lewis structure; helps assess stability (FC = valence electrons − (nonbonding electrons + 1/2 bonding electrons)).

Resonance hybrid

The actual structure is a blend of multiple valid Lewis structures; charges/delocalization are distributed across the molecule rather than fixed to a single atom.

Dipole moment / internal charges

Molecules can have regions of partial positive and negative charge (dipoles) even when the overall molecule is neutral.