How does the Heisenberg uncertainty principle contribute to the idea that electrons occupy 'clouds' or 'orbitals'?

1 Answer
Jun 6, 2017

According to the uncertainty principle, the position and the conjugate momentum of a particle such as an electron cannot be determined simultaneously to an arbitrary degree of accuracy.

What this means is that, when you try to figure out its position to somewhat accuracy, the momentum measurements become highly uncertain. Also, for a precise measurement of momentum, you pay the price of a pretty uncertain measurement in position.

In other words, the exact trajectory of an electron is indeterminate and this is a basic law of nature.

Is that an inadequacy in the theory or some error in the measuring instrument ?

No! Absolutely not! It is not possible to do it and it's the basic nature of the electron that you cannot make simultaneous measurements of position and momentum accurately.

Thus, the idea of definite path or orbits for an electron is out of question.

That's why people talk about orbitals and electron clouds.

In an orbital, the position or momentum of the electron is not defined. It's just a localised region where finding the electron is the most probable.

In quantum mechanics, you only talk about probability.