Bohr model & relativity on large atoms?

Click For Summary

Discussion Overview

The discussion revolves around the implications of relativistic effects on the mass of electrons in large atoms and how this relates to the Bohr model. Participants explore the relationship between electron speed, mass, and atomic mass in the context of relativistic quantum chemistry.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions why the relativistic increase in electron mass does not lead to a corresponding increase in the mass of large atoms, suggesting that this could cause a divergence from the expected proton/neutron mass values.
  • Another participant references "Relativistic Quantum Chemistry" as a source that addresses the initial question, specifically mentioning the Mrel and Bohr Radius equations.
  • A different viewpoint suggests that the relativistic increase in mass of electrons in heavier elements accounts for the observed atomic masses not aligning with simple multiples of proton and neutron masses in the periodic table.
  • One participant cautions that the Bohr model is primarily applicable to hydrogen-like atoms and highlights the problematic nature of the concept of relativistic mass.
  • Another participant agrees with the need for caution regarding the concept of relativistic mass while emphasizing its utility for understanding the underlying principles, even if limited to hydrogen electrons.

Areas of Agreement / Disagreement

Participants express differing views on the applicability of the Bohr model and the implications of relativistic mass, indicating that multiple competing perspectives remain without a clear consensus.

Contextual Notes

Participants note limitations regarding the applicability of the Bohr model to only certain types of atoms and the complexities surrounding the concept of relativistic mass, which may affect the overall understanding of atomic mass calculations.

Ruptor
Messages
18
Reaction score
0
Why Doesn't the increase in mass of the electrons, due to the relativistic correction required to prevent the calculated electron speed exceeding the speed of light, increase the mass of the atoms of the large elements? If the electrons were heavier on larger elements then the mass would diverge from the proton/Neutron value wouldn't it?
 
Physics news on Phys.org
So I guess the relativistic increase in mass of the faster electrons in heavier elements is the reason the atomic masses don't go up in nice multiples of proton+neutron+electron masses in the periodic table.
 
You have to be careful here:

- the Bohr model is good for hydrogen-like atoms only: Atoms with a single electron, and (with additional corrections) electrons with filled shells and a single outer electron.
- relativistic mass is a very problematic concept
- while a captured electron gains some kinetic energy, it loses more potential energy. In total, the system loses energy
- the overall effect on the mass of the combined system (~1MeV/c^2) is still below nuclear binding energies (some MeV/c^2 and nucleon).
 
Your very correct. But it helps to understand the concept, even if its only applicable to H electrons. Relativistic mass in this sense is still problamatic
 

Similar threads

  • · Replies 31 ·
2
Replies
31
Views
2K
  • · Replies 23 ·
Replies
23
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 9 ·
Replies
9
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 9 ·
Replies
9
Views
3K
  • · Replies 7 ·
Replies
7
Views
4K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 76 ·
3
Replies
76
Views
4K
  • · Replies 23 ·
Replies
23
Views
3K