PT Trend for Acidity

Another Periodic Table Trend to Remember: Acidity

Acidity increases down and to the right.

Here's why!

As electronegativity increases, acidity increases.

• Remember polarity?

• More electronegative atoms cause a greater dipole by pulling the electrons towards them.

• This makes it much easier for a hydrogen to be pulled off!

As bond strength decreases, acidity increases.

• The weaker the bond between an atom and it's hydrogen, the easier it is to pull the hydrogen off.

Multiple Choice

Which of these is the strongest acid?

• HCl

• HBr

• HI

• H₂Se

Multiple Choice

Which of these is the weakest acid?

• H₂Te

• H₂Se

• H₂Po

• H₂S

Multiple Choice

Which of these would have the weakest conjugate base?

• H₃P

• HAt

• HCl

• H₃As