C3. Acid-Base Chemistry 3

Question 1

How does structure determine acidity?

Answer 1

-Bond energies
-Electronegativity
-Inductive effects
-Hybridisation
-Resonance / delocalisation

Question 2

How do bond energies affect acidity?

Answer 2

-This controls the ease and extent to which the proton can be lost from the acid (i.e. the strength
of the acid)
-Bond strength weakens on descending group in periodic table
ONE NOTE

Question 3

How does electronegativity affect acidity?

Answer 3

Electronegativity increases across a row in the periodic table (from left to right). This increases acidity.
ONE NOTE

Question 4

What is an inductive effect?

Answer 4

The ability of a ligand to change electron density at a nearby atom via sigma bonds is known as
the inductive effect

Question 5

What are the two types of inductive effect?

Answer 5

1) Electron attracting ligands
- negative inductive effect (-I)
2) Electron releasing ligands
- positive inductive effect (+I)
ONE NOTE

Question 6

What is the resonance effect?

Answer 6

Ligands can also change electron density at a nearby atom via p
bonds, which is known as the resonance effect

Question 7

How can the inductive effect stabilise or destabilise the conjugate base

Answer 7

-electron withdrawing inductive effect stabilises anion
-electron donating inductive effect destabilises anion

Question 8

How does hybridisation affect acidity?

Answer 8

-The more s character of an orbital, the closer the electrons are to the nucleus, which is comparable to increased electronegativity of the atom
-Order of effective electronegativity in carbon:
sp > sp2 > sp3

Question 9

Describe how resonance affects acidity

Answer 9

ONE NOTE