Idm TBL Cycle 2 - Structure Of Organic Compounds

where is mostly all of the mass in a molecule ? in the extremely dense atoms what makes a molecule 3D ? negative and positive charges repelling why do same structures have more than to maximise attraction between opposite one arrangement ? charges what causes bonding in a structure ? define what an orbital is ? shape of orbitals overlapping each other an orbital is where an electron is likely to be found in an atom dictates the shape of a molecule how many electrons in 1 orbital ? 2 electrons how many S, P and D orbitals are present in a molecule ? 1s,3p,5d what is the shape of a S orbital ? sphere what is the shape of a P orbital ? lobe define orbital hybridisation ? atoms hybridise / mix atomic orbitals why do atoms hybridise orbitals ? to optimise the geometry and minimise energy of molecules name 3 hybridisation states ? sp , sp2 , sp3 hybridised = sigma what bonds do hybridised and unhybridised orbitals make ? unhybridised = pi bond which bond is stronger ? sigma or pi ? sigma bonds are stronger as they are closer to the nucleus which hybridisation state forms 1 sigma bond ? sp3 which hybridisation state forms 1 sigma and 1 pi bond ? sp2 which hybridisation state forms 1 sigma and 2 pi bonds ? sp what hybridised orbital do all 6 carbon atoms have in benzene ? all sp2 hybridised 1/4 how does the pi system work in benzene p orbitals delocalise giving a pi system ? focused on valence electrons describe the fundamentals behind the VSEPR theory ? ensure electrons are far apart from each other as possible what happens to the bond length as the bonds show more pi character ? bond length decreases what is a bond order ? number of formal bonds between any two atoms is known as the bond order what is the bond order of a bond in benzene ? 1.5 what is another name for structural isomers ? constitutional isomers what is a structural isomer ? compounds with the same molecular formula but different structural formula what are the 2 types of isomers called ? enantiomers and diastereoisomers what are stereoisomers ? compounds with the same structural formula but with a different arrangement of the atoms in space non-superimposable mirror images similar chemical property define enantiomers ? different in ability to rotate PPL + biological activity what is another name for enantiomers ? optical isomers where does the differences arise from enantiomers ? ability to rotate PPL contain 50% of each enantiomer define the term racemic mixture ? optically inactive ability to rotate the plane of polarised light 2/4 which 2 properties are different in a pair of enantiomers ? reaction / interaction with other enantiomeric compounds state the equation to find enantiomeric excess ? ee = % of one enantiomer - % of other enantiomer if an enantiomer is a positive / d form, then which way does it rotate the PPL ? clockwise if an enantiomer is negative / L form, then which way does it rotate the PPL ? anti-clockwise what are diastereoisomers ? stereoisomers that are not mirror images do diastereoisomers have different physical properties ? yes what are 2 types of diastereoisomers ? cis and trans rotation must be constricted what 2 things does a molecule need to have for cis and trans isomerism ? two identical what are meso compound and how many stereoisomers are expected from them ? what is a conformer ? rotation of single bonds in a molecule what method is used to visualise conformers ? newman projections which chemical produces 2 distinct conformers ? acetylcholine how many carbon atoms need to be in an aromatic ring for there to be subtle and distinct conformers ? four / five = subtle six - distinct hydrogens are eclipsed what are 2 features of a boat conformer ? torsional strain = atoms are close together all hydrogens staggered what are two features of a chair conformer ? no torsional strain 3/4 arrange the molecules so that the longest carbon chain is vertical with the highest priority group at the top what are the rules of drawing a fischer arrange the carbon chain so that each plane projection ? carbon atom goes away from the observer represent each bond as a simple line what letters are given to stereoisomers drawn in this projection ? D and L how do you find the group / atoms with the highest priority ? depends upon the atomic number with the atom of highest atomic number getting highest priority what does it mean if there is a double or triple bond ? both atoms are regarded as duplicated or triplicated c=c / c-c triple bond / c-c-c which way does R rotate ? clockwise which way does S rotate ? anti clockwise assignment of configuration - the (R) and (S) system ? what happens when lowest priority group is pointing towards the front ? view the chiral centre along the bond to the lowest priority atom lowest priority group is pointing towards the back of the paper if configuration is clockwise - it is flipped to anticlockwise if configuration is anticlockwise- it is flipped to clockwise why is picking the correct enantiomer im- different enantiomers have different or portant ? opposing effects 4/4