Topc 5: Chemical Reactivity Flashcards
Define nucleophile
A molecule which is electron-rich or which possesses a centre or region of high electron density
What do nucleophile often have as sources of electron density
Negative charge
Lone pair
pi bonds
Sigma bonds between atoms with large electronegativity difference
Are anions with localised or delocalised charge more nucleophilic
Localised
Nucleophilicity … from right to left on the periodic table because…
Increases
Electronegativity decreases causing electrons to give up electrons more easily
Nucleophilicity … down a group
Increases
The more electronegative an atom, the … electrophilic
Less
The more steric crowding there is around a reacting centre, the … its nucleophilicity
Lower
Protic solvents contain a … atom attached to a … atom
Hydrogen
Electronegative
Protic solvents are usually … and have a high …
Polar
Dielectric constant
Polar protic solvents solvate …
Nucleophiles
High level of solvation … nucleophilicity
Decreases
Many aprotic solvents posses a high … so are classified as … solvents
High dielectric constant
Polar
Aprotic solvents don’t contain functional groups that incorporate a … atom bonded to a … atom
Hydrogen
Electronegative
Polar aprotic solvents tend to be more efficient at solvating the … than the … so … are more reactive in polar aprotic solvents than polar protic solvents
Positively charged anions
Negatively charged anions
Negatively charged nucleophiles
Define electrophile (and electrophilic character)
A molecule which is electron deficient or possesses a centre or region of low electron density is said to have electrophilic character
