Introduction to Group 15, 16, 17, 18 (Part - 1) - P Block Elements, Chemistry, Class 12 Video Lecture

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objective of this lesson is to
appreciate the general trends in the
chemistry of elements of the group 15 16
and 17 elements you will study my p
block elements in p block elements will
be studying 15 16 17 and 18 groups group
13 in Houghton we have already started
in the previous class we learn how to
prepare dye nitrogen and phosphorus and
also some of its properties of important
compounds we will describe again the
preparation properties of and use of by
oxygen and ozone and chemistry of simple
oxides we will know the electrons
electrons from of sulphur when again
prepare chlorine HCl will also know the
chemistry of halogens and structures of
oxoacids of halogens we will understand
the use of noble gas will appreciate the
point of these all these elements and
they compound in our day-to-day life the
first question is what are people our
lives right so if you see this is the
periodic table this is s block on the
left hand side then you have P block
then you have D block and then you have
them so going by definition the P block
elements are the elements with the last
electron enters the outermost p orbital
reason that's why it's called P block
because the last electron interests the
outermost p orbital this you can easily
see from the electronic calculation
helium is the exception here helium is
considered to be in P block but actually
if you see helium helium the lock
doesn't have any p orbital so helium is
the only exception in fact this is a
debate on whether helium belongs to s
block and P draw with some textbook says
helium
in s-block some say is helium is in P
block but even in this case will
consider helium as P block although in
helium the last electron doesn't in turn
p orbital but the general definition is
if there are last electron enters s
orbital we classify them as s block the
last electron interest p orbital with
last them is P block the last electron
enters D orbital we classify them as D
block the last electron enters F orbital
we classify them as F block that is how
the classification is he M in the
exception helium since the properties of
helium is in the masses with the group
18 elements and do baten is in the P
block so we consider helium also in the
P block the next question is we know no
water P block element the next question
is why should we study people aqua
lipids so in this slide and talk about P
block group 15 16 17 and 18 elements
only because other elements we have
already discussed 13 and 14 we have
discussed so now I'm going to talk about
the uses of typically group 15 16 17 18
limits of the P block the first is Yuri
and fertilizes if you see nuyen
fertilizer nitrogen is used phosphorus
is use sulfur is used so all these are
my people on elements so if we talk
about human in human being the proteins
which we have then the muscles issue
build that is also nothing but my toes
the proteins and that is a P block
element in our refrigerant we use
nitrogen in rocket fuel we use nitrogen
in the food industry when you want when
you prepared soldering baking pot
etcetera you and phosphorus that is also
my P block element you want to make
insecticides weed killers so here we use
arsenic and arsenic is a
my pubic elements if you see the alloys
the alloys we used antimony also or not
antimony antimony is mine you block
element right if you talk about the
oxygen which we breathe made in which we
or the plants take oxygen this is again
oxygen is my P block element the most
critical element for our survival is
oxygen and this P block element if you
see the ozone layer that protects us
from the harmful UV rays right this zone
is my P block element ozone nothing but
you get ozone from oxygen oxygen is P
block element the vulcanized rubber you
get right this hardening of rubber you
is sulfur and sulfur is again P block
element the sulfuric acid most common ah
acid in the lab that has sulfur this is
P block a lipid there is oxygen the
throes of B block lipid right if you
talk about semiconductor in
semiconductor we use selenium and
selenium is also my P block element if
you talk about disinfectant of water we
use chlorine use chlorine for
disinfecting the water and chlorines
again my P block element I are in hiding
helps to maintain that or to secrete the
thyroid hormones right if you don't have
if you have deficiency of iron you get
this li is called goiter so here my
iodine that is used to prepare or to
produce thyroid hormones is again my P
block limit the common salt that we use
a lot in our daily life it has na+ and
cl- HCl is nothing but my P block
elements toothpaste toothpaste has not a
fluorine right this this chlorine is
nothing but my P block element if you
talk about lighting which you see lot of
shops is all neon or helium is used in
this case H they all know
block elimination if you see in this
case my knee or lightning or heliumetic
these are my three block records these
are some of the uses of please P block
pavement this is not the exhaustion list
and please don't have covered only group
15 16 17 and 18 here because group 14
and 13 is something you already
discussed there in class 11 so we are
some of the common use of p block
elements having understood the
criticality of Pedro element especially
nitrogen to build proteins not to build
proteins for a body or oxygen that is
the most critical element for our
survival
they started after of V block element
the first thing which I want to discuss
before even going forward with P block
element is a concept of inert pair
effect the only solid this effect in
class 11 but will repeat this see the
maximum oxidation state shown by any P
block him this might be long element all
the elements appear on elements is
typically the total number of valence
electron for example carbon the valence
electron is for correct 1s2 2s2 to be
due to the number of valence 2s2 2p2 we
talk about the second orbital the
maximum number of Alaska tourism for for
nitrogen ABC 1s2 2s2 2p3 so the maximum
number of electronics to +35 oxygen mu C
1 is to us to to be for maximum olivella
theta R is 6
similarly fluorine if you see one has to
do is to to be 5 to +5
cell so the maximum wearable electronics
M so typically the maximum oxidation
state shown by this P rock elements is
equal to the number of electrons on the
carbon shows maximum of +4 oxidation
state
nitrogen will show max
plus five oxidation states similarly
oxygen is so maximum of +6 oxidation
state correct but if you go down the
groom if you go down the group what
happens is the maximum oxidation state
is not shown for example if you talk
about b.i it will not show plus 5
oxidation state if we talk about SN it
may not to plus 4 oxidation state right
so what is happening is the moment you
go down as you go down the group
oxidation state of 2 units less than my
maximum efficiency or you can see the
group oxidation state for group carbon
the group oxidation state is for 4 group
nitrogen the group oxidation state is 4
right if I
similarly for group oxygen the group
oxidation number of oxygen statistics so
these elements down the group they don't
show the maximum value they show two
oxidation state less that is what does
seem experimentally right so these guys
may show and suppose this is may show +3
this may show +4 right so the question
is why why there is only a difference of
class 2 why why not why not difference
of 3 or 4 that experiment it is seen
that if you see these s has two orbit I
mean to move electron releases so the
justification even is and this is only
for my pee blood limits please note this
is only for my inert pair effect is only
for my people oh why I I'll tell you why
because if you see pre York elements
before this speed is s right and if you
go down the group what is happening your
size is increased right if you go down
the group size is increasing but your
charge is also increasing a lot right
the charge is increasing a lot so in
this case you go down the group the
charge increase a lot right charge
increase a lot size increase but the
charge increase more the the increase in
the nucleus charge is much more than
corresponding
in size right charge increase a lot size
increase okay you can say so with this
since it has both chart it has more
charge here they elect the atoms has
more charge it will hog the electrons it
will track the electrons and s orbitals
these S orbitals they are almost very
very near to the electrons these S
orbitals will not take part in the bond
since they will not take part in the
bond formation you have to ignore these
rocks efficiency because oxidation state
typical if example you say sio2 you see
carbon is +4 why because it's bonded to
two oxygen atoms correct so similarly
h2o you will say you will say oxygen is
-2 why because these oxygens bonded to
two hydrogen atom but when you go down
the groups in the charge is increasing a
lot and the size is okay take this okay
next increase in size so what is
happening here is this s orbital which
is just before this p orbital these as
orbiters they don't take part in the
bond formation so s orbital
you don't take part
bon voyage see anyway these will never
take part 1 s orbital because the
valence orbitals only take part in the
bond formation that is something we know
out of these valence orbital also these
s orbitals valence or against a balance
S orbitals yeah yeah typically all the
valence orbitals take part in the
reaction in the bond formation but in
this case as you go down something size
increase in the the charge increases a
lot and size increase little less so
these electrons are hot by the atoms and
the s orbitals actually they don't take
part the valence s orbitals they don't
take part in the bond formation so the
maximum oxidation state shown by the
lower or heavier elements in the group
is
- less than my group oxidation number
correct why I wanted to because this is
2x2 okay thank you
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