Brønsted–Lowry Theory
- The Brønsted-Lowry Theory defines acids and bases in terms of proton transfer between chemical compounds
- A Brønsted-Lowry acid is a species that gives away a proton (H+)
- A Brønsted-Lowry base is a species that accepts a proton (H+) using its lone pair of electrons
How an acid acts as a Brønsted-Lowry proton donor
The diagram shows a Brønsted-Lowry acid which donates the proton to the Brønsted-Lowry base that accepts the proton using its lone pair of electrons
- Species that can act both as acids and bases are called amphoteric
- Eg. water as a Brønsted-Lowry acid
Water acting as a Brønsted-Lowry acid
The diagram shows water acting as a Brønsted-Lowry acid by donating a proton to ammonia which accepts the proton using its lone pair of electrons
Dot and cross diagram showing the Brønsted-Lowry behaviour of water with ammonia
The diagram shows a dot & cross diagram for the reaction of water with ammonia to show how water acts as a Brønsted-Lowry acid and ammonia as a Brønsted-Lowry base
- Eg. water as a Brønsted-Lowry base
Water acting as a Brønsted-Lowry base
The diagram shows water acting as a Brønsted-Lowry base by accepting a proton from hydrochloric acid proton using its lone pair of electrons
Dot and cross diagram showing the Brønsted-Lowry behaviour of water with hydrochloric acid
The diagram shows a dot & cross diagram for the reaction of water with hydrochloric acid to show how water acts as a Brønsted-Lowry base and ammonia as a Brønsted-Lowry acid
- The Brønsted-Lowry Theory is not limited to aqueous solutions only and can also be applied to reactions that occur in the gas phase
A Brønsted-Lowry acid and base reaction
HCl acts as a Brønsted-Lowry acid by donating a proton while ammonia acts as a Brønsted-Lowry base by accepting a proton
Examiner Tip
- An atom of hydrogen contains 1 proton, 1 electron and 0 neutrons.
- When hydrogen loses an electron to become H+ only a proton remains, which is why a H+ ion is also called a proton.
