Heisenberg’s Uncertainty Principle – Chemistry Notes

Heisenberg’s Uncertainty Principle:

In 1927, Warner Heisenberg proposed the uncertainty principle. It states:

“It is impossible to state both position as well as momentum of electrons accurately and simultaneously”

To determine the position of electron more accurately, radiations of shorter wavelength should be used but according to de Broglie’s equation uncertainty in momentum will increase.

                                     λ = h/mc

If radiations of longer wavelength are used, uncertainty in momentum will decrease but then uncertainty in position of electron will increases.

Product of uncertainty in momentum and position can be given as:

                         Δ P . Δ X  = 2h        


∆P = uncertainty in momentum

 ∆x = uncertainty in position

 h = Plank’s constant           

Thus idea of Bohr that electron move in definite orbit with definite momentum is not correct.

Heisenberg gave the idea of probability of electrons in an orbit.

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