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Q & A: magnetic effects and octet rule?

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Most recent answer: 08/22/2010
Q:
hi there..... i have to ask something...... for an atom the magnetic field experienced by the innermost orbital is the maximum due to its other orbitals having electrons moving……in almost the same direction….so they will attract this orbit…..hence help to maintain stabity…. Further wen the last orbital is reached the magnetic field from the other end would not exist so that is ready for bonding and hence new bonds are formed…..or should say orbitals are overlapped to maintain the balance……In this sort of understanding ….nowhere the need to have 8 electrons in the last shell is felt……can u explain from where the concept of octate or duplate help in stability come from……… i was wondering if the stability of an atom can be explained with the magnetic fields they create...... plz do reply
- apurva (age 17)
india
A:
The effects of magnetic fields on the energy of different electron configurations are rather small, especially for small atoms. The reason is essentially that the speeds of the electrons are low compared to c, and magnetism is just the velocity-dependent component of electricity required by Special Relativity. So the octet rule and other important chemical effects are not consequences of magnetic fields.

The numbers of electrons which can be placed in different energy "shells" depends instead on the numbers of distinct types of wave function shapes which have a given energy. The lowest energy states (with the fewest wiggles) are spherically symmetric. They hold two electrons because the two spin states are distinct.

(Bonds between atoms tend to contain two electrons, because if there is a low-energy waveform, it can fill with two electrons of opposite spins.)

Adding a wiggle to the state can give a different spherically symmetrical state or 3 distinct states with one unit of angular momentum. Allowing for spin makes a total of 8 different states.

Things get more complicated as one looks at atoms with even more electrons, because the interactions between the electrons become more and more important.

Mike W.

(published on 08/22/2010)

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