Particles & Size: Matter Structure & Wave Function

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In summary, particles have a defined size (relative to other particles) depending on the kind of particle. It is unclear whether an electron has a defined size.
  • #1
alvarogz
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What does a particle be small or big (in relative terms). Do particles have a defined structure? I thought that it is probably because in the particle accelerators they collide, so they have a material structure.
My doubt is related with the concept behind what Matter really represents. Is a electron smaller than a proton or a neutron? Is that question well proposed?.
The inclusion of the wave function of this tiny particles sometimes makes think if particles, at that level, are allowed to define a concept of size.
 
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  • #2
The answer depends on the kind of particle.

Atoms and molecules are very tiny, but have size of order 10^-10 m (for hydrogen atom) and this is confirmed by many experiments.

On the other hand, there is no convincing experiment which would suggest the size of an electron. Therefore, the most simple and used view of electron is that it is point-like.
There are also some attempts to build theories in which it has some small radius, but these are very complicated and so far not very useful.

For proton, the mainstream view is that is has size of order 10^-15 m, but the exact value is less clear than in the case of the atom.
 
  • #3
Protons and neutrons are composite particles, made from quarks and gluons. Electrons are elementary.
 
  • #4
I think it is quite tricky to define the 'size' of particles when talking about very small things due to their tricky quantum nature.

One way of thinking about it could be that when you are looking at the particle ( ie probing it with something - photons of light or electrons in a particle collider ) you are essentially probing it with something that has a wave-particle duality. So there is a de-broglie wavelength associated to your particle.

\lambda_{DB} = \frac{h}{p}

So you can tell whether the particle looks point like or not up to a certain length scale ( \lambda_{DB} ) which is defined by how powerful your probe is (its momentum).

Aside;
In reality it is a bit more complicated I think. For example an electron could be thought of a small ball of electric charge. But the little ball of charge will look differently depending on how energetic a particle you probe it with ( like a high energy photon vs a very very high energy photon )
 

1. What are particles in the context of matter structure?

Particles are tiny units of matter that make up everything in the universe. They can be atoms, molecules, or subatomic particles such as protons, neutrons, and electrons.

2. How do particles contribute to the size of an object?

The size of an object is determined by the arrangement and number of particles it contains. For example, a larger object will have a greater number of particles compared to a smaller object.

3. What is the wave function of a particle?

The wave function of a particle is a mathematical description of its properties, including its position, momentum, and energy. It is used in quantum mechanics to predict the behavior of particles at the subatomic level.

4. How does the size of a particle affect its properties?

The size of a particle can greatly influence its properties. For instance, smaller particles tend to have more energy and are more likely to exhibit quantum effects, while larger particles behave more like classical objects.

5. How do scientists study the structure of particles?

Scientists use various tools and techniques such as particle accelerators and microscopy to study the structure of particles. They also rely on mathematical models and theories to understand the behavior of particles at different sizes.

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