Intro to Organic Chemistry – Alkanes & Hydrocarbons

27 vocabulary flashcards covering key terms from the lecture on organic chemistry fundamentals, focusing on hydrocarbons, alkanes, naming rules, structural representations, physical properties, and combustion.

Organic compound

A molecule that always contains carbon and hydrogen and may also include other non-metals such as O, S, N, P, or halogens.

Hydrocarbon

An organic compound composed solely of carbon and hydrogen atoms.

Saturated hydrocarbon

A hydrocarbon in which all carbon–carbon bonds are single bonds (e.g., alkanes).

Alkane

A saturated hydrocarbon whose IUPAC names end in –ane; general formula CnH2n+2.

Cycloalkane

A cyclic alkane whose carbon atoms form a ring; general formula CnH2n.

Functional group

A specific group of atoms bonded in a characteristic way that imparts distinct physical and chemical properties to organic molecules.

IUPAC system

The International Union of Pure and Applied Chemistry’s standardized method for naming organic compounds.

Greek prefixes (naming)

Numerical prefixes (meth-, eth-, prop-, but-, pent-, hex-, etc.) used to indicate the number of carbon atoms in the main chain.

Condensed structural formula

A representation that groups each carbon with its attached hydrogens, e.g., CH3CH2CH3 for propane.

Line-angle formula

A zig-zag drawing where each vertex or line end represents a carbon atom; hydrogens on carbons are omitted for simplicity.

Expanded structural formula

A formula that shows every atom and every bond in the molecule.

Conformation (of alkanes)

Different spatial arrangements of atoms produced by rotation around C–C single bonds.

Structural isomer

Compounds with the same molecular formula but different connectivity of atoms.

Alkyl group

An alkane fragment that is attached to a chain; named by replacing the –ane ending with –yl (e.g., methyl, ethyl).

Haloalkane (alkyl halide)

An alkane in which a halogen atom (F, Cl, Br, I) replaces a hydrogen atom.

Halogen substituent names

Fluoro-, chloro-, bromo-, and iodo- are used to denote F, Cl, Br, and I substituents, respectively.

Substituent numbering

In IUPAC naming, carbon atoms in the main chain are numbered to give substituents the lowest possible set of locants.

Boiling-point trend (alkanes)

Boiling point increases with longer carbon chains due to greater dispersion forces.

Branching effect on boiling point

Branched alkanes have lower boiling points than their straight-chain isomers because branching reduces surface contact.

Dispersion forces

Weak intermolecular attractions arising from temporary dipoles; dominant force between non-polar hydrocarbon molecules.

Volatile liquid alkanes

Alkanes with 5–8 carbons that readily vaporize at room temperature; useful as fuels like gasoline.

Paraffins

Solid alkanes with 18 or more carbons that are waxy at room temperature.

Petroleum jelly

A semisolid mixture of hydrocarbons containing more than 25 carbon atoms.

Combustion of alkanes

Reaction of an alkane with O2 to yield CO2, H2O, and energy; e.g., CH4 + 2O2 → CO2 + 2H2O + energy.

Methane

The simplest alkane (CH4); a tetrahedral molecule and primary component of natural gas.

Propane

A three-carbon alkane (C3H8) commonly used as a bottled fuel.

Cycloalkane naming rule

For a single substituent, its name is placed before the cycloalkane name with no number (e.g., methylcyclohexane).