Concept of boson and fermion applied to atoms and more

In summary: Helium-4 does display superfluidity. I'm not sure if liquid hydrogen displays superfluidity because the molecules are not large enough or if the behavior is specific to the particular type of hydrogen.
  • #1
fluidistic
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Sometime I read that the helium atoms can be considered as boson, but I don't understand why. I know that its nucleous has a spin of 2 (integer) and that its 2 electrons gives the atom a total spin of 3, an integer.
But then why isn't hydrogen considered also as a boson? I think it's considered as a fermion, like the electron itself. Why? The total spin of the H atom isn't 1 (thus an integer)? It seems like only the nucleous is the only important thing in deciding whether an atom can be considered as a boson or fermion, why is it so? And if I have a molecule, how do I determine whether it's a boson or fermion?
In Wikipedia one can read
Wiki the Great said:
(they follow different quantum statistics: helium-4 atoms are bosons while helium-3 atoms are fermions).
and also
Wiki the Giant said:
In particle physics, bosons ( /ˈboʊsɒn/[1]) are subatomic particles with integer spin (s = 0, 1, 2 etc.) that are governed by Bose-Einstein statistics.
where the enphasis is mine.
Can someone explain me when I can call a particle/atom/molecule a boson?
 
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  • #2
It depends on spin. Composite particles with an even number of fermions is a boson with integer total spin. Particles composed of an odd number of fermions is a fermion with half-integer total spin.

A proton by itself is a fermion ( 3 quarks). A hydrogen atom has four fermions- 3 quarks and an electron- and is considered a boson.

ETA:
A hydrogen molecule (H2) consists of two bosons and is a boson.

That wiki page should read particle.
 
Last edited:
  • #3
Jimmy said:
It depends on spin. Composite particles with an even number of fermions is a boson with integer total spin. Particles composed of an odd number of fermions is a fermion with half-integer total spin.

A proton by itself is a fermion ( 3 quarks). A hydrogen atom has four fermions- 3 quarks and an electron- and is considered a boson.

ETA:
A hydrogen molecule (H2) consists of two bosons and is a boson.

That wiki page should read particle.

Ok thank you very, very much! So in a way I'm either a fermion or boson. :tongue:
 
  • #4
I'm also wondering about something related. So hydrogen molecules are bosons. However, when they interact, do they behave as bosons? Why does liquid hydrogen not display superfluidity as helium, both the 3 and 4 versions do?

Is there a size scale at which composite bosons no longer display the properties of bosons?
 
  • #5
chill_factor said:
I'm also wondering about something related. So hydrogen molecules are bosons. However, when they interact, do they behave as bosons? Why does liquid hydrogen not display superfluidity as helium, both the 3 and 4 versions do?

Is there a size scale at which composite bosons no longer display the properties of bosons?

Hydrogen freezes before it can get superfluid.
 

1. What are bosons and fermions?

Bosons and fermions are two types of fundamental particles that make up the building blocks of matter. Bosons are particles with integer spin, such as photons and gluons, while fermions are particles with half-integer spin, such as electrons and protons.

2. How are bosons and fermions applied to atoms?

In atoms, bosons and fermions play important roles in determining the properties and behavior of the atom. Bosons, such as photons, are responsible for holding the atom together through electromagnetic interactions, while fermions, such as electrons, determine the chemical and physical properties of the atom.

3. What is the difference between bosons and fermions in terms of their behavior?

Bosons and fermions behave differently due to their distinct quantum mechanical properties. Bosons can occupy the same quantum state, while fermions cannot. This leads to the phenomenon of Bose-Einstein condensation for bosons, where large numbers of particles can occupy the same state, whereas fermions follow the Pauli exclusion principle, which prohibits multiple fermions from occupying the same quantum state.

4. How are bosons and fermions applied to more complex systems than atoms?

Bosons and fermions play crucial roles in more complex systems, such as molecules and materials. In molecules, the interactions between bosons and fermions determine the structure and properties of the molecule. In materials, fermions are responsible for the electrical conductivity and magnetic properties, while bosons contribute to phenomena such as superconductivity and superfluidity.

5. What are some practical applications of the concept of bosons and fermions?

The concept of bosons and fermions has many practical applications in various fields, including electronics, materials science, and quantum computing. For example, transistors, which are essential components of electronic devices, rely on the behavior of fermions. Superconductors, which have many technological applications, are based on the behavior of bosons. In quantum computing, the manipulation of bosons and fermions is used to process and store information in quantum bits (qubits).

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