What is the bronsted lowry definition of an acid?

An acid is the specie which can donate a proton.

Explanation:

Bronsted lower acid:

An acid is the specie which can donate a proton.

Bronsted lower base:

A base is the specie that can accept the proton.

For example:

HCl + NH₃     →       NH₄⁺ + Cl⁻

Here in this reaction HCl is act an acid because it donate the proton while NH₃ is Bronsted lower base because it accept the proton.

Bronsted lowery acid = proton donor

Bronsted lowery base = proton accepter

why do the isotopes of a particular element behave differently in nuclear reactions but the same in chemical reactions? chemical reactions involve changes to electrons in an atom; isotopes do not differ in electrons, and so they react the same way during chemical changes.