Key Terminology
Term Definition
Organic Chemistry Study of compound containing carbon
Homologous Series Series of compounds similar in structure, in which each member differs from the
next by common repeating unit CH2
Molecular Formula Gives actual numbers of atoms of each element in a compound
General Formula States number of each element in a compound relative to of C atoms
Structural Formula Specifies exactly how atoms are bonded in a compound
Displayed Formula Shows all bonds and atoms in a molecule
Skeletal Formula Lines to represent bonds. Each bond it a C atom. Ends assumed to occupied by
hydrogen. All other elements represented with chemical symbols
Structural Isomer Isomers with the same molecular formula but a different structural formula
Stereoisomers Isomers with the same molecular formula and structure but a different position
of atoms in space
Nomenclature
C atoms form strong covalent bonds to each other, which can be single, double or triple. C atoms can
be arranged in straight chains, branched chains and rings. Other atoms can be placed on the C atoms
in different positions.
Members of a homologous series share a general formula, a functional group, causing similar chemical
properties, and see a gradual change in physical properties.
Structural isomers can have the same functional group at different points – positional isomerism,
different functional groups – functional group isomerism, or a different arrangement of the chain –
chain isomerism. Naming rules apply as below.
IUPAC Naming Rules
• Identify longest carbon chain, counting number of carbons and name
• Identify side alkyl groups attached to main chain e.g. methyl, ethyl, propyl
• Number C atoms where branches are attached by starting at the end giving the lowest numbers
• Structural isomers arise from placing a functional group in different positions
• When two or more of the same group is present, use the di, tri, tetra prefixes
• With multiple functional groups or substituents, numbers are separated by commas and the
groups are listed in alphabetical order
Reaction mechanics can be notated using curly arrows to sow movement of an electron pair and dots
to indicate a radical species
