basic concepts Flashcards
what is a hydrocarbon?
A compound containing carbon and hydrogen only.
What does saturated mean?
Only has single bonds.
What does unsaturated mean?
Contains C-C multiple bonds.
What does homologous series mean?
A family of compounds with same general formula and functional group with successive members that differ by the addition of a CH2 group.
What is a functional group?
The part of the organic molecule that is largely responsible for the molecule’s chemical properties.
What is an aliphatic structure?
Carbons atoms are joined together to each other in unbranched (straight) or branched chains.
Alicyclic structure
Carbon atoms are joined to each other in ring structures, with or without branches.
Aromatic structure.
Some or all of the carbon atoms are found in benzene rings.
What is homolyctic fission?
Breaking a covalent bond, where each bonded atom receives an electron, forming radicals.
Difference in boiling points of branched and unbranched alkane.
Unbranched - more surface area points of contact, so stronger london forces, more energy needed to boil.
Branched - least surface area points of contact, so weaker london forces, least amount of energy to boil.
Molecular formula.
Shows the number and type of atoms of each element present in a molecule.
Empirical formula.
The simplest whole number ratio of the atoms of each element present in a compound.
What is a sigma bond the result of and where is it positioned?
- Result of the overlap of two orbitals, one from each bonding atom.
- Positioned on line directly between bonding atoms.
Reasons for lack of reactivity of alkanes.
- High bond enthalpy : C-C and C-H sigma bonds are strong.
- C-C bonds are non- polar.
- low polarity.
Conditions for free radical substitution.
- UV light.
Initiation for Br2 and methane.
Br-Br -> 2Br•
UV on top.
Propagation of methane and bromine.
1) CH4 + Br• -> •CH3 + HBr
2) •CH3 + Br2 -> CH3Br + Br•
Termination of bromine and methane reaction
Br• + Br• -> Br2
CH3• + Br• -> CH3Br
CH3• + CH3• -> C2H6
What does curly arrow represent?
Shows movement of electron pairs when bonds are being broken or made.
What does fish-hook arrow represent?
Represents the movement of a single, unpaired electron in mechanisms involving radicals.
Two reasons why there are many organic products of the reaction between bromine and ethane.
1 - Different radicals can combine to produce C4H10 or Br2, not bromoethane.
2 - Further substitution can occur, making compounds such as dibromo, tribromo etc.
