The electrons are negatively charged and the nuclei are positively charged. Why didn't the electrons fall into the nuclei?

It's not that the electrons don't fall to the nucleus, but typically they don't fall to the nucleus, otherwise the atom is too unstable. But under the right conditions, electrons can fall to the nucleus, but it takes a lot of energy.

Here's a layman's explanation of why this is so.

First of all, say the scientists study atomic model, which the rutherford model "planet" a representative, he through the alpha particle scattering experiment demonstrated that most of the atomic internal space is vacant, accounts for only a small number of nuclei in the center, and smaller electrons revolve around the nucleus, just like the earth around the sun.

But according to Maxwell's theory of electromagnetism, electrons lose energy by releasing electromagnetic waves as they move 39bet-kết quả bóng đá-kết quả xổ số miền bắc-kèo bóng đá -soi cầu bóng đá-đặt cược, and their orbits get lower and lower until they fall to the nucleus. But that doesn't occur.

Then Rutherford's student, Bohr, came up with a new model of the atom: electrons, with their own fixed orbits, do not radiate waves most of the time, but only when they make a transition, so that they can keep going. And the energy of the electron transition is not constant, it has to be in pieces

But Bohr's electron transition theory still had a flaw, and it worked just fine for hydrogen atoms, but as the elements got bigger and bigger, the errors got really ridiculous.

Then came Bohr's student Heisenberg, who famously submitted the uncertainty principle: the electron does not have a fixed orbit, its position is random and can only be characterized by probability, and this is where the electron cloud comes from.

The uncertainty principle demonstrates that we cannot measure the exact position and velocity of the electron at the same time, and the observation behavior will also alter the state of the electron.

​Subsequently, the famous physicist Pauli submitted the Pauli exclusion principle: two identical fermions (that is, elementary particles such as electrons, which are fermions) cannot be in the same quantum state, which is commonly understood to be in the same position.

Pauli's exclusion principle says that there's a force called electron degeneracy pressure, which makes sure that two electrons that are distinct are in the same quantum state, the same orbital, and there can't be more than two electrons in each orbital, so that they don't fall into the nucleus.

In general, electron degeneracy pressure is the limit at which something can be compressed. But this limit can be broken under special circumstances, such as a supernova.

The energy of a supernova blast is immense, large enough to crack the limit of electron degeneracy pressure, allowing electrons to fall to the nucleus and combine with protons to form neutrons, which is where neutron stars come from, or even, at higher energies, black holes!

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