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Why are Iron, Cobalt and Nickel Magnetic?

by FeDeX_LaTeX
Tags: cobalt, iron, magnetic, nickel
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FeDeX_LaTeX
#1
Apr14-10, 12:46 PM
P: 427
Hello;

Why are only iron, cobalt and nickel magnetic, and not any other material? Is it due to their unique electron configurations, or due to something else?

Thanks.
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DrDu
#2
Apr15-10, 02:25 AM
Sci Advisor
P: 3,560
There are other magnetic materials, like Gadolinium and e.g. ferrites and many more substances at lower temperatures.
Matterwave
#3
Apr15-10, 03:50 AM
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P: 2,671
The atoms in ferromagnetic materials like to align their magnetic dipoles with the external field.

Think for example 10 atoms that have randomly distributed magnetic dipoles. Since the dipoles are pointing in random directions, the magnetic field is nearly zero. However, if the material is ferromagnetic, once one introduces a mild external magnetic field, those dipoles line up and you get a strong magnetic field.

Other materials have atoms which don't tend to line their magnetic dipoles as much. Although, in a strong enough magnetic field, almost any material can become magnetic.

Gerenuk
#4
Apr15-10, 06:31 AM
P: 1,060
Why are Iron, Cobalt and Nickel Magnetic?

I think FedeX asks an interesting question which you haven't understood. In chemistry class we learned it's really only these 4 out of 100 elements that are ferromagnetic (at room temperature?) and no other! Moreover ferrites contain iron so it's no surprise.

It has to do with electron configuration, but I don't know the answer. I hope someone can enlighten us :)
FeDeX_LaTeX
#5
Apr15-10, 07:20 AM
P: 427
Thank you for the replies. I was not aware that gadolinium was magnetic. However, I would also like to know if electron configuration plays a major role.

Also, is this how magnets are usually made? By applying an additional external magnetic force? So how was the first magnet created?

Thanks.
mate0
#6
Apr15-10, 08:28 AM
P: 22
all atoms have electric charges inside of them, this is what pulls the electrons toward the nucleus. I don't know why some elements can extend the magnetic field beyond each individual atom while others can't.

yes that is how most magnets are made. the first magnets came from the earth, as some minerals have magnetic fields that are already lined up by earths own field. (google rare earth magnets for more info)

sort of related question: do ferromagnets and electromagnets produce the same type of field or is there a difference other than just the strength?
DrDu
#7
Apr15-10, 09:05 AM
Sci Advisor
P: 3,560
The named elements have a d-shell (or f-shell in case of rare earth magnets), which isn't completely filled and hence have a net spin moment. These spins in turn polarize the spins of the conduction electrons. The conduction electrons are not localized, so that they in turn also tend to polarize the d-electrons on neighboring atoms. This mechanism is called itinerant magnetism. However, the polarization of the conduction electrons oscillates as a function of the distance from the central atom and also of the filling of the conduction band. In favorable cases, this mechanism leads to an interaction which stabilizes parallel orientation of the spins on neighboring atoms and thus ferromagnetism. In other elements, like chromium, the spins align antiparallel, so that no net magnetic polarization results. Other elements simply lack the open d-shell while other elements are ferromagnetic in principle, but the effect is weak so that their Curie point is below room temperature (e.g. Holmium).
cragar
#8
Apr16-10, 10:16 AM
P: 2,464
Paramagnetism
cragar
#9
Apr18-10, 06:28 AM
P: 2,464
liquid oxygen is also magnetic , I would like to know what causes the magnetic field in a neutron. And when iron is heated red hot ,a magnet wont stick to it . This is why at the steel mill they have to pick up the slabs with tongs when they are hot , but when they cool you can pick them up with an electromagnet.


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