Organic chemistry Flashcards
Define molecular formula
expresses the exact composition of a molecule or substance
define empirical formula
the simplest whole number ratio of atoms of each element in a compound
define heteroatom
any atom which is not carbon or hydrogen
define constitutioanl isomers
they vary in structure through their arrangement of atoms
what is the difference between the labels isopropyl and propyl
isopropyl is when the bond from the main carbon chain is connected to the middle carbon on the propyl chain, rather than the first
how do you name an ether
identify the shortest chain, put oxy on the end, end the word with the longest chain
what is the difference between an ether and an ester
an ether has an oxygen atom in the chain of carbons, but an ester has an oxygen in the chain, and the next carbon is connected to an oxygen via a double bond
define polar covalent bond
when two atoms are bonded covalently but they have significantly different electronegativities and so the more electronegative atom finds the pair of electrons closer to it
define electronegativity
the tendency of an atom to attract a shared pair of electrons towards itself
list all of the types of bonds from strongest to weakest
covalent, ionic, metallic, hydrogen, dipole-dipole, london dispersion
why do longer alkanes have a higher melting/boiling point than shorter ones
the longer the chain, the more attractive forces per molecule, meaning more energy is required to break the intermolecular forces
why do alkanes float on water
they are less dense, non-polar, and hydrophobic
what do alkanes form in their solid state
a wax
why do branched alkanes have lower melting and boiling points then their linear isomers
they have substituted chains which are not able to pack as efficiently
define conformations
the different arrangements of atoms in a molecule in space due to rotation
do eclipsed or staggered newman projections have higher energy
eclipsed as lower distance between the eclipsing atoms
what are the three types of ring strain
angle - angles deviate from 109
torsional - methyl groups on adjacent carbons eclipsed
steric - methyl on non-adjacent carbons are too close
define axial bonds
the six axial bonds, one on each carbon in a ring, are parallel and alternate up and down
define equatorial bonds
the six equatorial bonds, one on each carbon in a ring, come in three sets of two parallel lines, they also alternate between sides around the ring
are axial or equatorial bonds higher in energy
axial
why are carbon-carbon sigma bonds stronger than carbon-carbon pi bonds
they are less susceptible to electrons
why are there more trans isomers than cis
they are thermodynamically more stable due to steric strain existing in the cis form
what is the difference between E and Z isomers
E - higher ranked groups are on opposite sides
Z - higher ranked groups are on the same side
define stereoisomers
same atomic connectivity but differ in special arrangement of the constituent atoms
define enantiomers (optical isomers)
non-superimposable mirror images of each other, and are said to be chiral
define optically active
it rotates plane polarised light
define diastereoisomers
either member of a pair of substances that differ with respect to the configurations of their molecules
name the four types of organic reactions
addition, elimination, substitution, rearrangement
what are the two types of bond formation
homolytic (symmetrical) and heterolytic (unsymmetrical)
define concerted reaction
a chemical reaction in which all bond breaking and making occurs in a single step
define electrophile
electron pair acceptor
define nucleophile
electron pair donator
describe the reaction of hydrochloric acid with ethene
the alkene behaves as a nucleophile and the proton from HCl behaves as an electrophile. The pi bond on the alkene breaks and the two electrons form a new bond with the proton. A carbocation is formed, which then behaves as an electrophile for the Cl-, forming a bond
