Magnetic Properties of Transition Metals:(part - 1) Video Lecture - NEET

transition metals their complexes and
magnetic properties you need to learn
these three words ferromagnetic that has
the biggest interaction with a magnetic
field paramagnetic and then diamagnetic
which has the weakest interaction with a
magnetic field now what causes these
sorts of magnetism well is to do with
the number of lone electrons in orbitals
and to do with the number of paired
electrons in orbitals let's start off
with ferromagnetic you need to learn
that there are three metals that are
ferromagnetic iron cobalt and nickel
iron is 4s 2 3 D 6 cobalt is 4s 2 3 D 7
and nickel is 4s2 3d8
you also need to use the word domains
these metals form domains so what's a
domain well looking at the one at the
bottom left there that little arrow
there showing the domain that one if you
look closely all of the nickel in that
domain those electrons are going to be
lined up with the domain which electrons
the lone electrons which are responsible
for this ferromagnetic property and so
when you put a ferromagnetic material in
a magnetic field it's strongly attracted
now this stuff is tricky but I'm going
to go through it several different ways
so let's look at the difference between
paramagnetic and diamagnetic materials
I've got some transition metals there
and some ions also if they're alone
electrons in orbitals it's going to be
paramagnetic so as I fill out these
orbital diagrams anything with lone
electrons is paramagnetic now that isn't
quite as magnetic as ferromagnetic but
it's still attracted to magnets
Plus that has no lone electrons in
orbitals only has paired electrons so
that's diamagnetic that actually
slightly repulsive towards magnets but
copper two-plus R that has one lone
electron and so that is going to be
paramagnetic so let's look at some real
world examples I'm going to bring a
magnet close to silver chloride and that
doesn't seem to be attracted to it so it
can't be ferromagnetic or paramagnetic
then if it's not tracted to the magnet
so silver chloride has a plus one charge
on its iron let me take off that
electron there to show silver plus yep
only pairs of electron so it must be
diamagnetic manganese two chloride or
look at that it's slightly magnetic now
let me show the electronic configuration
for the manganese 2 plus iron oh yes
it's got lots of lone electrons there so
it's actually paramagnetic cobalt 2
chloride
yep that's magnetic - let me take off
those two electrons to make it the
cobalt 2 plus iron yep it's got lone
electrons there must be paramagnetic and
finally nickel nickel has lone electrons
it's paramagnetic no no no no it's
ferromagnetic you have to learn iron
nickel and cobalt ferromagnetic and
there are those domains again and
finally an unpleasant little detail that
the IB may ask about let's look at these
two complexes here first of all I
wouldn't work out the D orbital for
those two iron ions the first one has an
oxidation state of iron of +2 and the
second one also has a +2 oxidation state
for iron I like them let me just draw
those arrows in the boxes
so you think that they would both be
paramagnetic because they have lone
electrons their iron ions not iron iron
ions iron is ferromagnetic these are
iron ions paramagnetic oh that one's
diamagnetic now after this very second
you thought that diamagnetic was only
paired electrons exclusively paired
electrons so how does that work out well
let's look at the spectrochemical series
from the ib copywrite ib table 15 and
you can see that fluoride is there and
carbon monoxide is at the very right
hand side so that's going to give a much
bigger split i'm gonna put it right up
there
so because the energy difference is so
big with the carbon monoxide the
electrons can't maintain that very high
energy up in those boxes they're going
to come down to the lower boxes and so
actually the one with the cover monoxide
ligand is diamagnetic because those
single electrons go down and pair up
with the other single electrons tricky a
and so some questions which is the most
paramagnetic which is diamagnetic so
paramagnetic need at least one electron
in an orbital on its own
so only scandium is paramagnetic
which are diamagnetic diamagnetic every
electron must be paired in the orbitals
okay so scandium 3 plus titanium 4 plus
and all my lord so we're looking for the
nickel here because they're doing
transition metals so it's a plus 4
oxidation state which is 3d 6 now that's
got lone electrons also are but this is
super high split cyanide gives a very
high split it's high up in the
spectrochemical series so those
electrons tumbled down to pair up at the
bottom that's diamagnetic to nasty a