Why does Z=-1 for a beta minus particle?

[JCsponge]

This sounds like a silly question but if

Z (atomic number) is defined as the number of protons in a nucleus.

Why does Z=-1 for a beta minus particle? (since it is just an electron)

I know what is happening with the decay that a up quark turns into a down quark so that a neutron turns into a proton, electron and electron neutrino but I see no reason other than saying the atomic number must be conserved in the decay equation for Z=-1 for the beta particle.

It seems to me that we have decided that Z=-1 to fit a rule for conservation of atomic number and for no other reason.

I know that there must be an error in my thinking somewhere but where?

 

[malawi_glenn]

You can also define Z as the number of positive charged entities within a nucleus. Hence when the nucleus are gaining one positive charged entity (neutron -> proton ) one negative charge must "fly away" (electron + neutrino). So it depends on how you define Z.. it's not a big deal - the most important thing is that you understand the physics and that what is important is electric charge conservation.

There are many funny and strange notations in physics, many are historical.

 

[sir-pinski]

The reason for Z = -1 for a beta minus particle is not just to fit a rule for conservation of atomic number. It is actually a result of the fundamental properties and interactions of subatomic particles.

First, let's understand what happens during beta minus decay. In this process, a neutron in the nucleus decays into a proton, an electron, and an antineutrino. The neutron is made up of two down quarks and one up quark. One of the down quarks in the neutron changes into an up quark, resulting in a proton. The other down quark emits a W- boson, which then decays into an electron and an antineutrino.

Now, the electron that is emitted during beta minus decay is not just any electron. It is a high-energy electron, also known as a beta minus particle. This is because during the decay process, the W- boson transfers energy to the electron, giving it a high velocity.

So, why does Z = -1 for this beta minus particle? This is because the electron is not a part of the original nucleus. It is created during the decay process and is not bound to the nucleus. Therefore, it does not contribute to the atomic number of the nucleus. The atomic number of the nucleus remains the same as before the decay, which is why Z = -1 for the beta minus particle.

In summary, the reason for Z = -1 for a beta minus particle is not just to fit a rule, but it is a result of the fundamental properties and interactions of subatomic particles. The electron emitted during beta minus decay is not a part of the original nucleus and therefore does not contribute to its atomic number.