Acids and bases: several useful definitions
Arrhenius, Brønsted–Lowry and Lewis definitions are not competitors: they describe progressively broader contexts.
Start with the idea
Arrhenius, Brønsted–Lowry and Lewis definitions are not competitors: they describe progressively broader contexts.
A concrete example
NH₃ is a Brønsted base because it can accept a proton even though its formula contains no OH⁻ ion.
Mendeleev’s tip
Do not start with a formula. Identify what changes, what stays constant and which quantity you are trying to explain or calculate.
Go one step deeper
In NH₃ + H₂O ⇌ NH₄⁺ + OH⁻, NH₃ accepts a proton and H₂O donates one, revealing the conjugate acid-base pairs.
A trend or model is not an exceptionless law. Always check the quantity’s definition and the conditions being compared.
Check your understanding
Can you explain the phenomenon in your own words before looking at an equation?