Q 26:
Explain the following with
suitable examples:
(i) Ferromagnetism
(ii)Paramagnetism
(iii)Ferrimagnetism
(iv)Antiferromagnetism
(v)12–16
and 13–15 group compounds.
Solution:
(i) Ferromagnetism:–
Ferromagnetism: few substances like iron, cobalt, nickel, gadolinium and
CrO2 are strongly attracted by a magnetic field. Such substances are
known as ferromagnetic substances. These substances can be permanently
magnetised with the help of strong electrostatic field. The metal ions of ferromagnetic substances
are grouped together into small regions called domains in solid state. So that each domain acts as a tiny
magnet. The domains of un magnetized
piece of a ferromagnetic are randomly oriented so that their magnetic moments
get cancelled out. When such substance is placed in a magnetic field, all the
domains get oriented in the direction of the magnetic field and a strong magnetic effect is produced.
This ordering of domains remains same
even when the magnetic field is removed and the ferromagnetic substance
becomes a permanent magnet.
(ii) Paramagnetism :–
few substances like O2, Cu2+, Fe3+, Cr3+ are weekly attracted by a magnetic field.
These substabces are magnetised in a magnetic field in the same direction.
When we remove magnetic field ,they lose their magnetism. paramagnetism is
takes place due to presence of one or more unpaired electrons. These unpaired
electron are attracted by the magnetic field.
(iii)Ferrimagnetism:
This effect is observed when the
magnetic moments of the domains in the substance are aligned in parallel and
anti–parallel directions in unequal numbers. Ferrimagnetic substances are weakly attracted by magnetic field
as compared to ferromagnetic substances. Magnetite like Fe3O4 and ferrites like MgFe2O4
and ZnFe2O4 are examples
of such substances. On heating these substances lose their ferrimagnetism
and become paramagnetic.
(IV)Antiferromagnetism:
Antiferromagnetic substances have
domain structure similar to ferromagnetic substance. The domains of antiferromagnetic substance are oppositely
oriented and cancel out each other's magnetic moment . Example MnO is a
Antiferromagnetic substance.
(V)12–16 and 13–15 group compounds.
The compounds of 12–16 group are
prepared by combining elements of group 12 and group 16. While the compound of
13–15 group compounds are prepared by combining elements of group 13 and group15. These compounds are
covalent and there ionicity depends up the difference in electro negativities
of elements which involve in forming of these compounds. These compounds have
special electrical and optical properties so that these compounds are used in
industries for a variety of applications
Examples
ZnS, CdS ,CdSe and HgTe are example of 12–16 group compounds
InSb, AIP and GaAs are the example of 13–15 group compounds
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ReplyDelete
ReplyDelete(a) predator-prey relationship?
(b)parasitism
(c)mutualism