0
$\begingroup$

I know that azimuthal quantum numbers and magnetic quantum numbers are used to find the no. of and the orientation of subshells respectively, but why do they have to be called so?

I reckon that azimuth means the angle w.r.t North or something but have no idea so as to why magnetic quantum no. has to be called so, doesn’t the spin of an electron determine its magnetic properties? So won’t the spin quantum number be a better choice to express the magnetic properties? How does the 3D orientation of orbitals have something to do with the term ‘magnetic quantum number’? Similarly for azimuthal quantum no. and it’s relation with the no. of subshells .

$\endgroup$
0
$\begingroup$

The awnser to this lies in the Angular Momentum. The electron has charge, and charged particles in motion produce a magnetic field, related to their angular momentum. Therefore, not only the electron spin has a magnetic momentum. That's why these quantum numbers are given these names. If you want know more, search about spin-orbit coupling, this is an effect produced by the coupling of the spin magnetic moment with the orbital magnetic moment.

| improve this answer | |
$\endgroup$
  • $\begingroup$ I'm afraid I don't follow your answer. (1) What is "magnetic momentum"? (2) How does that relate to the name "azimuthal"? (3) What does spin-orbit coupling have to do with any of this? The azimuthal and magnetic quantum numbers are $l$ and $m_l$ respectively, we aren't even beginning to deal with spin here. $\endgroup$ – orthocresol Jul 27 at 4:27
-1
$\begingroup$

The spin of an electron is like the daily rotation of the Earth. The magnetic quantum number is like the yearly revolution of the Earth around the Sun. Both carry angular momentum. This angular momentum is typically measured by applying a magnetic field, which is sensitive to rotation within one particular plane, or equivalently around one particular axis that is perpendicular to that plane - the "North-South" axis. If the electron in any way turns around the axis one way, as a moving charge it produces a magnetic field aligned with the external magnetic field, but if it turns the other way it will be opposite to that field. Increasing the total magnetic field in the region takes energy, which can be seen by spectroscopy as absorption of higher-frequency light. Electron spin resonance (ESR) will measure the energy difference when an electron flips the direction of its spin, while the Zeeman effect measures the difference between positive and negative magnetic quantum number.

Under ordinary circumstances where powerful magnetic fields are absent, the direction of an electron's spin is unknown (typically written as an up arrow in molecular orbital diagrams when it is unpaired), while the complex-valued solutions for electron density for + and - magnetic quantum numbers are added together to represent the real-valued standing wave produced by these two electrons. That standing wave is the lobed p, d, or f orbital depending on the absolute value of the magnetic quantum number.

| improve this answer | |
$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.