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Chemistry - Module 4 - Basic Concepts and Hydrocarbons - Part 1 - Coggle…
Chemistry - Module 4 - Basic Concepts and Hydrocarbons - Part 1
organic chemistry basics and representations
ways to represent organic compounds
molecular formula shows actual atom counts
structural formula shows atom connectivity by labelling each C one at a time
empirical formula shows simplest-whole number atom ratio
skeletal formula shows carbon skeleton and functional groups, omitting H and C from being visually shown
general formula gives algebraic family description
organic chemistry focuses on groups of similar chemicals called homologous series
homologous series members share a functional group and a general formula
consecutive members differ by a -CH2- unit
classification of carbon frameworks
aromatic compounds contain a benzene ring
aliphatic compounds are straight/branched chains or non aromatic rings (alicyclic)
homologous series and nomenclature
common homologous series and functional groups
prefix/suffix: alkanes (-ane); alkenes (-ene); haloalkanes (chloro-, bromo-, iodo-); alcohols (-ol); ketones (-one); carboxylic acifd (-oic acid); esters (alkyl-...-anoate); cycloalkanes (cyclo-...-ane); aldehydes (-al)
IUPAC naming rules
identify main functional group to determine suffix, number chain to give lowest number to main group
add side-chains as prefixes, list in alphabetical order, use di-/tri-/tetra- for multiples
choose longest continuous carbon chain for the stem (meth-, eth-, prop-, but-, pent-, etc)
if multiple chains give same length choose the one with most side-chains
isomerism
structural isomer subtypes
positional isomers have the same skeleton but functional group at different carbon locations
functional group isomers have different functional groups and markedly different properties
chain isomers differ in carbon skeleton branching, affecting physical properties like boiling point
definition and major types
isomers share a molecular formula but differ in atom arrangement
structural isomers have different connectivities; stereoisomers have same connectivity but different spatial arrangement
stereoisomers overview
arise from restricted rotation (e.g. about C=C) leading to different spatial arrangements
alkanes: structure, properties and reactions
combustion and incomplete combustion
complete combustion: alkane + O2 -> CO2 + H2O; releases large amount of energy making alkanes useful fuels
in limited oxygen, incomplete combustion produces CO and H2O; CO is poisonous because it binds readily to haemoglobin
physical properties and intermolecular forces
small alkanes are gases with low boiling points; larger alkanes are liquids with higher boiling points
london forces increase with chain length and surface area; branching reduces boiling point by decreasing surface contact
structure and bonding
general formula CnH2n+2 for alkanes, cycloalkanes CnH2n
each carbon forms a tetrahedral with bond angle 109.5 degrees, for single (sigma) bonds present
bond fission and radical substitution
photochemical free-radical substitution with halogens requires UV light and proceeds via initiation, propagation, termination
propagation involves using radicals to form more radicals
termination involves radicals forming a stable product
initiation involves the formation of radicals
heterolytic fission yields ions; homolytic fission yields radicals with unpaired electrons
practical issues; mixture of products and positional substitution; excess alkane reduces by-products