Organic chemsitry Flashcards
Define electronegativity
A chemical property which describes the tendency of an atom to attract a shared pair of electrons towards itself
What is the electronegativity of carbon?
Low, so it will share its electrons
What are the two main categories of carbon compounds?
- aliphatic (either alicyclic or acyclic)
- aromatic
Describe the difference between aliphatic and aromatic molecules?
- aromatic are always unsaturated whereas aliphatic can be saturated or unsaturated.
- aromatic are always cyclic whereas aliphatic can be linear aswell
- aromatic need special conditions to react whereas aliphatic can react more freely and easily
Define a heteroatom
Any atom not hydrogen or carbon
What is a homologous series?
A group of organic compounds with similar structural formulae and similar properties but whose formulae differ by a constant component
What happens to energy when bonds are formed?
Energy is released and the system becomes more stable
Name the first 4 alkanes
methane (CH4)
ethane (C2H6)
propane (C3H8)
butane (C4H10)
What are isomers?
A compounds with the same molecular formula, but different molecular structures
What are the rules in naming alkanes?
- identify longest carbon chain
- identify branches on this chain, name them according to no. c atoms they contain e.g. methyl, ethyl
- number the carbon atoms on longest chain to describe the positions of the branches
- write branches in alphabetical order
What is the formula for alkanes?
CnH2n+n
What is the formula for alkenes?
CnH2n
What is the formula for alkynes?
CnH2n-2
Describe the difference in bonds between alkanes, alkenes and alkynes
alkanes= all carbon double bonds are single bonds alkenes = at least 2 carbon atoms are joined by a double bond alkynes = at least 2 carbon atoms are joined by a triple bond
Name some common functional groups
alcohol, alkene, alkane, alkyne carboxylic acid, ester,
Describe the reactivity difference between alkanes and alkenes?
Alkanes are not very reactive but alkenes are very reactive due to double bond
What is hybridisation?
the mixing of atomic orbitals into new hybrid orbitals
How are atomics formed?
From sp2 (1 s orbital and 2p orbitals) hybrised carbon atoms joined in a 6 membered ring e.g. benzene C6H6
What is the orbital structure of carbon?
1s2,2s2,2p1,2p1
Name the two ways in which atoms can be arrange differently in a compound
trans, opposite orientations, across
Cis = same spatial orientations, on the same side
What is stereo isomerism?
all atoms in the compounds are attached to the same partners, but the partners are arranged differently in space
What is geometric isomerism?
the isomerism shown by some alkenes because there is no free rotation about the double bond
What is optical isomerism?
organic molecules can exist in two forms that are mirror images of one another- they are super imposed
What is the ‘chiral centre’ in terms of optical isomerism?
The carbon atom where it is bonded to four different atoms or groups
