definitions

Question 1

Electrophile

Answer 1

Any atom, molecule or ion that accepts a pair of electrons from a nucleophile to form a new covalent bond.

Question 2

Nucleophile

Answer 2

Any atom, molecule or ion that gives a pair of electrons to a electrophile to form a new covalent bond

Question 3

Addition reactions

Answer 3

two atoms or small groups add across the double bond. Only pi bond and one sigma bond are replaced by two sigma bonds.

• first step is slow - bc need to put energy in to break the bond
• second fast.

Question 4

Regioselective reaction

Answer 4

occurs with non-symmetric alkene.

• The regioselectivity an be stated as Markovnikov’s rule
  
  • In the addition of HX to an alkene, the hydrogen adds to the carbon atom of the double bon that already bears the greater number of hydrogen atoms.

Question 5

Aromatic

Answer 5

• all planar with an odd number of electron pairs in the pi system
• resonance structure - delocalized bonding
• flat molecule
• must have at least one unhybridized p orbital on each atom of the ring

Question 6

Electrophilic aromatic substitution reactions

Answer 6

require a catalyst because the electrons want to stay where they are

Question 7

Alcohols

Answer 7

good leaving groups are H2O bc fairly unreactive.

-OH and CH3 not good

Question 8

Ethers

Answer 8

R1-O-R2

• isomeric with alcohols but have different properties
• polar, can’t H bond, unreactive

Question 9

chirality

Answer 9

• four different groups attached to a carbon
• non-superposable
• mirror image is called enantiomer
• all physical properties are the same except spatial placement of atoms

Question 10

Reaction rate

Answer 10

• quantitative definition of the speed of a chemical reaction in terms of appearance of products or disappearance of reactant
• positive for product and negative for reactant

Question 11

Factors that affect reaction rate

Answer 11

• temp
• concentration
• physical state of reactant
• presence of catalyst

Question 12

instantaneous rate

Answer 12

• rate at a particular time

- determined by measuring the slop of the concentration vs time at same point on graph

Question 13

initial reaction rate

Answer 13

-instantaneous rate at t=0

Question 14

Activation energy

Answer 14

• minimum energy required to initiate a reaction.. Causes changes in bonding in a given reaction
• Rate depends on activation energy

Question 15

Activation complex

Answer 15

• transition state where bonds are partially broken or/and partially formed
• unstable - can reform into previous state or into new bonds

Question 16

Rate determining step

Answer 16

governs rate law for overall reaction

-slow step is the determining step

Question 17

heterogenous catalysis

Answer 17

• catalyst in a different phase from reacting molecules (almost always solid)
• adsorption -> diffusion -> surface reaction -> desorption