P block elements 1

 IONIZATION ENTHALPY (IE or H):
 Ionization enthalpy also shows irregular
trends. On moving down the group, IE
decreases from B to Al, but the next element
Ga has slightly higher ionization enthalpy
than Al due to the poor shielding of
intervening d-electrons. It again decreases in
and then increases in the last element .

 ELECTRONEGATIVITY:
 Down the group the electronegativity
decreases from B to Al and then
increases marginally. This is due to
the noticeable difference in atomic
size of elements.
ELEMENT ATOMIC RADIUS/pm ELECTRONEGATIVIT
Y
B 88 2.0
Al 143 1.5
Ga 135 1.6
In 167 1.7
Tl 170 1.8

 INERT PAIR EFFECT:
 The phenomenon of electrons remaining
paired in valance shell is called inert pair
effect.
 It is the reluctance of the s-electron of the
valance shell to take part in bonding. It
occurs due to poor or ineffective shielding of
the ns2 – electrons of the valance shell by
intervening d and f – electrons. It increases
down the group and thus, the lower elements
of the group exhibit lower oxidation states.

 OXIDATION STATES:
 B and Al show oxidation states of +3 only while
Ga, In and Tl exhibit oxidation states of both
+1 and +3.
 As we move down in the group 13, due to inert
pair effect, the tendency to exhibit +3 oxidation
states decreases and the tendency to attain +1
oxidation states increases.
 Stability of +1 oxidation state follows the order
Ga<In<Tl.

F
B F
F
+ NH3
F
B
F
F
NH3
 LEWIS ACIDS:
 Boron trifluoride is trivalent molecule of boron. The
number of electrons around central boron atom in
this molecule is only six. It has incomplete octet.
Therefore this is electron deficient molecule and
has tendency to accept lone pair of electrons to
achieve stable inert gas electronic configuration.
Thus it behaves as Lewis acid.

 Stability in AlCl3 is formed due to the
formation of dimer.
 Dimer: It is a molecule or molecular complex
consisting of two identical molecules linked
together.
Al Al
Cl
ClCl
Cl
Cl
Cl
10
1 79 11
8

 Action of Air (oxygen): Amorphous Boron
on heating in air forms B2O3 ,boron oxide.
eg: 4B + 3O2
1000K 2B2O3
Boron trioxide
 Reactivity towards Halogens: Boron
reacts with halogen to form Trihalides.
eg: 2B+ 3Cl2 2BCl3
Boron trichloride

 Reactivity towards Water: Pure boron
does not react with water. Aluminum
decomposes boiling water evolving
hydrogen.
eg: 2Al + 6 H2O 2Al(OH)3 + 3H2
Gallium and Indium are not attacked by
pure, cold or hot water. Thallium is a little
more reactive than Gallium and forms an
oxide on the surface.

 Boron is a nonmetal while other members
are metals.
 Boron shows allotropy while other members
do not.
 Amongst the elements of group 13, boron
has highest M.P. and B.P.
 Boron forms only covalent
compounds(maximum covalence of boron is
3) while other members form both ionic and
covalent compounds.

 Oxides and hydroxides of boron are weakly
acidic, of aluminium are amphoteric while those
of rest of members are most basic.
 Boron hydride is quite stable while hydrides of
other elements are less stable.
 Only boron combines with active metals such
as Mg to form borides while rest of the
members do not.
3Mg + 2B Mg3B2
Magnesium Boride
Crystalline boron is unreactive

 Boron with alkali
Boron dissolves with alkali , to give borates
with evolution of H2 gas.
2B + 6NaOH 2Na3BO3+3H2
Reaction with acids:-
2B + 3HNO3 H3BO3+3NO2

 Sum of the first three ionization enthalpies is less, as
compared to Boron. this is due to the easy tendency to lose
electrons It is able to form Al 3+.
 In the other elements, due to poor shielding effect of d and f
orbitals, the nucleus holds the outer most s electrons tightly.
Thus, only p bonding may be available for bonding.
 In all 3 elements, both +1 and +3 oxidation states are seen.
 The compounds in +1 state are more ionic than those in +3
state.

 Aluminum forms a very thin oxide layer.
With di nitrogen at high temperatures
they form nitrides.
 It dissolves in mineral acids and
aqueous alkalies and thus show
amphoteric character.
 All the group 13 elements except
thallium show reactivity towards
halogens.

 2E(s) + 3O2(g) 2E2O3(s)
 2E (s) + N2(g) 2EN(s)
 [ E = element ]
 2Al(s) + 6HCl (aq) 2Al3+(aq) + 6Cl-(aq) +
3H2(g)
 2E(s) + 3X2(g) 2EX3 (s)

Borax
It is the most important compound of boron. It is a white
crystalline solid of formula Na2B4O7⋅10H2O. Borax dissolves
in water to give an alkaline solution.
Na2B4O7 + 7H2O 2NaOH + 4H3BO3
Orthoboric acid
On heating, borax first loses water molecules and swells up.
On further heating it turns into a transparent liquid, which
solidifies into glass like material known as borax bead.
Na2B4O7.10H2O Na2B4O7 2NaBO2+
B2O3
sodium
metaborate

SP3 ATOMS UNDERGO HYTBRIDAZATION.THERE ARER
FOUR TERMINAL B-HT NORMAL COVALENT BONDS WHICH ARE QUITE
STRONG (ALSO CALLED TWO CENTRAL ELECTRONE
PAIRE BOND OR TWO CENTRE TWO ELECTRONE BONDS
I.E 2C-2E) AND TWO BRIDGE B….HB …B WHICH ARE
DIFFERENT FROM NORMAL COVALENT BONDS AND
ARE QUITE WEAK (ALSO CALLED three centre electron
pair bond or three resemblance to a banana these are
also called banana bond.

 Boron being extreamly hard refractory solid
of high melting point,low density and low
electrtical Conductivity, finds many
applications. The main industrial application
of borax and boric acid is in the manufacure
of heat resistant glasses (eg. Pyrex ),glass
wool and fibre glass.borax is used in flux for
soldering of metals,for heat,scratch and
stain resistant glazed coating to
earthenwares and as consituent of
medicinal soaps.an aqueous solution of
orthoboric acid is generally used as a mild
antiseptic.

Aluminium is a bright silvery white metal with high
tensil strength.it has high eletrical and thermal
conduccytivity. Aluminium forms alloy with
Cu,Mg,Mn,Fe,Ni,Co.
Aluminium is a chief constitiunt of silvery paints.
Alums are used in purification of water. It also
used in sizing of papers.it acts as septic to stop
bleding.it is quite used in deying and tanning of
leather.alums have good application in
dehydration,decolouraton and chromatography.

 Reaction with acid
 Aluminium dissolves in dil. or con.Hcl
and dil.H2so4 SLOWLY LIBERATING H2 GAS
WHILE CONC.H2SO4 GIVES SO2 GAS.
 2Al+ 6HCL(dil.) + 12H2O
2[Al(H2o)]cl3 3H2

 ALUMINIUM DISSOLVES IN NAOH OR
KOH TO FORM META-ALUMINATE WITH
THE EVOLUTION OF H2 GAS.
 2Al + 2naoh+ 2H2o 2NaAlo2+ 3H2

 Carbon(C), silicon(Si),
germanium(Ge), tin(Sn) and
lead(Pb)are the elements of
group 14.

 C and silicon are non metals. Ge
is a metalloid whereas Pb and Sn
are metal.
 Carbon is seventeenth most
abundant element by weight in
the earth crust and forms many
compounds than any other
elements except hydrogen.

Carbon has two stable isotopes 12C(98.9%)
and 13C(1.1%). It is widely distributed in
nature in free state as
well as in the
combined form.
Carbon has third
isotope as 14C. It is
radioactive and
used for radiocarbon dating.

 In elemental form it is available in coal, graphite,
diamond.
Coal diamond graphite
 In combined form it is available as metal
carbonates, hydrocarbons, and carbon dioxide gas
(0.03%) in air. Carbon is versatile element in the
world.

Fats, carbohydrates, proteins, vitamins,
etc. and fossil fuels such as petroleum,
lignite, are made up of carbon
compounds, carbon is essential
constituent of all living organisms.

 Silicon is the second (27.7% by mass) most abundant
element in the earth crust. It is present in nature as
silica(SiO2) and silicates. It is a very important
component of ceramics, glass and cement.

Germanium exists only in traces. Tin
occurs as SnO2 (cassiterite or
tinstone) and lead as galena(PbS).
Ultrs pure germanium and silicon
are used in making transistors and
semiconductor devices.

Electronic Configuration
 The valence shell electronic
configuration of these element is
ns2np2.
 The inner core of the electronic
configuration of element in this group
differs.
 Hence C and Si has inert gas core. Ge
and Sn have inert gas core plus 10d-
electronput Pb has inert gas core plus
10d-electron and 14f-electron.

ELEMENT
SYMB
OL ATOMIC.NO
ELECTRONIC
CONFIGURATIO
N
Carbon C 6 [He] 2s2 2p2
Silicon
Si
14 [Ne] 3s2 3p2
Germanium
Ge
32 [Ar] 3d10 4s2 4p2
Tin Sn 50 [Kr] 4d10 5s2 5p2
Lead Pb 82 [Xe] 5d10 6s2 6p2

 Here we are considering atomic radii,
ionization enthalpy, electronegativity and
physical properties. Electronic
configuration of group 14 is shown in
table11.7.

 Atomic radii of these
elements regularly increase
as we move down the
group primarily due to addition of new
every shell at each succeeding element.
 The increase in atomic radii from Si
onwards is however, small due to
ineffective shielding of the valence
electrons by the intervening d- and f-
electron.

 The ionization enthalpy of group 14 element
is higher than the corresponding elements
of group 13 due to increased nuclear
charge.
 The influence of inner core electrons is
visible . In general the ionization enthalpy
decreases down the group.
 Small decrease in ∆H1 from Si to Ge to Sn
and slight increase in ∆H1 from Sn to Pb is
consequence of poor shielding effect pf
intervening d and f orbitals and increase in
size of atom.

 Due to small size, the
element of this group are
slightly more
electronegative than the
corresponding
group 13 element.
 The electronegativity
decreases as we
move down the group but
not after silicon.

 The electro negativity values for elements
from Si to Pb are almost the same. Carbon
with electronegativity of 2.5 is the most
electronegative element of group 14.

 The group 14 elements have four electrons in the
outer most shell. All the elements show an oxidation
state of +4.
 However as we move down the group from C
to Pb, the stability of +4 oxidation state
decreases while that of +2 oxidation state
increases due to inert pair effect .

• Carbon also exhibits negative
oxidation states. Since the
sum of first four ionization
enthalpies is very high,
compounds in +4 oxidation
states are generally covalent in
nature.
• In heavier elements the tendency to show +2
oxidation state increases in order Ge<Sn<Pb.
• It is due to the inability of ns2 electron of
valence shell to participate in bonding.
• Carbon and silicon mostly show +4 oxidation
state.

Germanium forms stable compounds in +4 oxidation state and
very few compounds in +2 state.
Tin forms divalent as well as tetravalent compounds. Sn in +2
state is reducing agent. Lead compounds are stable in +2 state.
Lead in +4 oxidation states acts as oxidizing agent (PbO2).
Carbon show maximum covalence as four. Other elements,
because of the presence of d orbitals, show covalence more than
4

 All the group 14 elements are solids.
Carbon and silicon are non metals,
germanium is metalloid, where as tin and
lead are soft metals with low melting
points.

 The m.p and b.p of group 14 elements are higher than those of
corresponding elements of group 13. This is due to strong interacting
binding forces in their solids as well as in liquid states. Down the group,
there is regular decrease in m.p and b.p
as the size of atoms
increases and interatomic
forces of attraction decreases.
Hence silicon is hard while
lead is a soft metal.

Allotropes are different physical forms of the same
element which have same chemical properties but
different physical properties, and the phenomenon is
known as Allotropy.

Carbon can bond with itself in at least
three different ways giving us 3 different
materials
 Diamond
 Graphite
 Buckminster-fullerenes

 A diamond is something known as an allotrope.
 An extremely hard, highly refractive crystalline formof c
arbon that is usually colourless and is used as
gemstone and in abrasives, cutting tools, and
other applications.

 Carbon has an electronic
arrangement of 2,4. In diamond,
each carbon shares electrons with
four other carbon atoms - forming
four single bonds.
 In the diagram some carbon atoms
only seem to be forming two bonds
(or even one bond), but that's not
really the case. We are only
showing a small bit of the whole
structure.

 High melting point due to strong directional
covalent bonds (3550 C).
 Extremely hard because it is difficult to break
atoms apart or move them in relation to one
another.
 No electrical conductivity because electrons are
localized in specific bonds.
 Insoluble in polar and non-polar solvents
because molecular bonds are stronger than any
intermolecular forces.

A soft crystalline allotrope of carbon, composed
of graphene layers, having a steel-gray to Black
metallic luster and a greasy feel, used in lead pencils,
lubricants, paints.

 Each carbon atom is only covalently bonded to three
other carbon atoms, rather than to four as in diamond.
 Graphite contains layers of carbon atoms.
 Graphite has a layer structure which is quite difficult
to draw convincingly in three dimensions. The diagram
below shows the arrangement of the atoms in each
layer, and the way the layers are spaced.

 Has a high melting point, similar to that of
diamond.
 Has a soft, slippery feel, and is used in pencils
and as a dry lubricant for things like locks.
 Has a lower density than diamond.
 Conducts electricity. The delocalised electrons
are free to move throughout the sheets.
 Is insoluble in water and organic solvents.

A fullerene is a pure carbon molecule composed of at
least 60 atoms of carbon. Because a fullerene takes a
shape similar to a soccer ball or a geodesic dome, it
is sometimes referred to as a buckyball .

 They consist of hexagonal rings of carbon
atoms (like in graphite or graphene) and
alternating pentagonal carbon rings to allow
curvature of the surface
 The carbon-carbon bonds in Buckminster
Fullerene C60 form a pattern like a soccer ball
and this fullerene is a brownish-reddish-
magenta colour when dissolved in organic
solvents.

 The molecule can act as a semiconductor, conductor
and superconductor under specific conditions
 Fullerenes can display the photochromic effect,
which is a change in light transmission based on
intensity
 Is essentially insoluble in polar solvents,
sparingly soluble in alkanes
 Fullerenes are relatively safe and inert, and yet have
properties that allow the substance to create active
derivatives

 Direct combination of carbon in limited
supply of air or oxygen gives carbon
monoxide
2C(s)+O2 2CO(g)
C
O
Carbon monoxide is both short-lived in atmosphere and spatially variable in
concentration
Chiefly it is a product of volcanic activity but also man-made fires, burning of
fossil fuels also contributes to carbon monoxide production

 Chemical formula- CO
 Appearance- Colorless
 Odor- Odorless
 Solubility- soluble in chloroform, acetic acid, ethyl
acetate, ethanol, ammonium, hydroxide, benzene
 A powerful reducing agent and reduces almost all
the metal oxides other than alkali and alkaline earth
metals and few transitional elements
 It is used in extraction of many metals from their
oxides

Fe2 O3 +3CO 2Fe(s) +3CO2(g)
CuO(s) + CO(g) Cu(s) + co2(g)
ZnO(s) + CO(g) Zn(s) +
CO2(g)
Iron oxide + Iron + carbon dioxideCarbon
monoxide
Copper oxide
+
Carbon
monoxid
e
copper+ carbon
dioxide
Zinc oxide
+
Carbon
monoxide
Zinc
+
Carbon
dioxide

Hemoglobin carries
oxygen and carbon
dioxide
Hemoglobi
n
Red Blood
Cell
Carbon
monoxide binds
very tightly to
hemoglobin
O2 and Co2 can
no longer be

)
∆
∆
2) It is prepared in the laboratory by the action of
dilute HCl on calcium carbonate.
∆
KHATIJA
11.17.2 TILL SILCON DI OXIDE

3)On commercial scale, it is obtained by heating
lime stone.
4) It is valuable byproduct in the manufacture of ethyl
alcohol by fermentation of glucose and fructose

It is a colourless and odourless gas .Its low solubility in water makes it of great biochemical
and geo chemical importance.
With water it forms carbonic acid which is a dibasic acid and disassociates in two steps
H2CO3/HCO3
- buffer system helps to maintain pH of blood between 7.26 to 7.42.

sunlight
453-473K
220 atm Ammonium carbonate

SILICON TETRACHLORIDE SiCl4
Silicon tetrachloride is the
inorganic compound with the
formula SiCl4. It is a
colourless volatile liquid that
fumes in air. It is used to
produce high purity silicon
and silica for commercial
applications

It is prepared by action of chlorine
on silicon
Si + 2Cl2 SiCl4
This tetrahalide is covalent in nature
and possess tetrahedral geometry.
The tetra chloride of carbon i.e.CCl4
is not hydrolysed by water but SiCl4
gets easily hydrolysed.
CCl4 +H2O No reaction
SiCl4 + 4H2O Si(OH)4 + 4HCl
orthosilicic acid

EXPLANATION
Silicon and carbon both are the
members of 14th group. But
Silicon tetrachloride reacts with
water while carbon
tetrachloride does not . this is
due to the fact that the
carbon does not have d -
orbitals to accept lone pair of
electron from water while
silicon has vacant d - orbitals
to accept lone pair of electron
from water.

SILICONES
Silicones are polymers that include
any inert, synthetic compound made
up of repeating units of siloxane,
which is a chain of alternating silicon
atoms and oxygen atoms, frequently
combined with carbon and/or
hydrogen. They are typically heat-
resistant and rubber-like, and are
used in sealants, adhesives,
lubricants, medicine, cooking
utensils, and thermal and electrical
insulation. Some common forms
include silicone oil, silicone grease,
silicone rubber, silicone resin, and
silicone caulk.

FORMATION OF SILICONES
Effective lubrication is provided by
an interfacial monomolecular film of
coadsorbed dimethylsilicone and
fatty acid molecules. This film
continues to maintain low friction
and wear with increasing
temperature due to the reaction of
the acid with the metal surfaces and
the subsequent formation of the
high-melting-point copper soap.
Electrical resistance measurements
show this to be due to the formation
of a thin non-conducting interfacial
film, which provides protection for
the sliding surfaces up to
temperatures in excess of 150°C.

Soup ladle and
pasta ladle are
made up of
silicones
A silicone food steamer
to be placed inside a pot
of boiling water
Ice cube trays made of silicon

SILICATES
A silicate is a compound containing an
anionic silicon compound. The great
majority of silicates are oxides, but
hexafluorosilicate ([SiF6]2−) and other
anions are also included.
"Orthosilicate" is the anion SiO4
4− or its
compounds. Related to orthosilicate are
families of anions (and their
compounds) with the formula
[SiO2+n]2n−. Important members are the
cyclic and single chain silicates
{[SiO3]2−}n and the sheet-forming
silicates {[SiO2.5]−}n.
Silicates comprise the majority of
Earth's crust, as well as the other
terrestrial planets, rocky moons, and
asteroids.

The main applications were in detergents, paper,
water treatment, and construction materials

STRUCTURE OF SILICON TETRACHLORIDE

Silicates
Feldspar -NaAlSl3o8
Mica- KH2Al3(Sio4) or KAl3Si3O(OH)
Zeolite – Na2O.Al2O3.XSiO2.YH2O
Structure of silicate:-silicates are is sp3of
SiO4 tetrahedral units silicon is Sp3
hybridized and surrounded by 4 oxygen
atoms
When all four corners are shared with other
tetrahedral units, a three dimensional
network is formed and –ve charge on silicate
structure is neutralized by +vely charge
metal ions.

ZEOLITES
Zeolites are microporous, aluminosilicate
minerals commonly used as commercial
adsorbents and catalysts.The term zeolite was
originally coined in 1756 by Swedish
mineralogist Axel Fredrik Cronstedt, who
observed that upon rapidly heating the material
stilbite, it produced large amounts of steam from
water that had been adsorbed by the material.
Based on this, he called the material zeolite, from
the Greek ζέω (zéō), meaning "to boil" and λίθος
(líthos), meaning "stone".
Zeolites occur naturally but are also produced
industrially on a large scale. As of July 2015, 229
unique zeolite frameworks have been identified,
and over 40 naturally occurring zeolite
frameworks are known.[

Zeolites are widely used as ion-exchange
beds in domestic and commercial water
purification, softening, and other
applications. In chemistry, zeolites are
used to separate molecules (only
molecules of certain sizes and shapes can
pass through), and as traps for molecules
so they can be analyzed.

P block elements 1

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