Allotropes of Carbon Video Lecture - Class 10

allotropes of carbon
carbon is a well-known non metallic
chemical element which is present in all
life forms the element carbon occurs in
different forms in nature with wide
variety of physical properties it is
abundantly found in the Earth's crust
let's now try to have a better
understanding of carbon and its
compounds carbon is represented by the
symbol C its atomic number is 6 that is
it contains six protons and six
electrons carbon exists in two forms
crystalline in amorphous in crystalline
solids the constituent particles are
arranged in a definite order but in
amorphous solids the Constituent
particles have no definite order of
arrangement coal coke and charcoal are
amorphous forms of carbon and diamond
graphite and fullerene are crystalline
forms of carbon both these forms are
called allotropes of carbon allotropes
are forms of the same element which
exhibit different physical properties
but with the same chemical composition
let's now classify carbon according to
its shape structure and physical
properties accordingly let us understand
the crystalline forms diamond diamond is
a hardest crystalline form of carbon in
diamond each carbon atom is linked to
four other carbon atoms by covalent
bonds forming a rigid 3-dimensional
structure each c2c bond length is 154
p.m. diamonds density is equal to 3.5
grams per CC here no electrons are
available as they are involved in bond
formation because of the absence of free
electrons diamond is a bad conductor of
electricity
diamond has a high melting point of 4000
Kelvin or more let's now learn about
other crystalline allotropic forms of
carbon in Free State graphite in
graphite each carbon atom is linked to
three other carbon atoms by covalent
bonds resulting in hexagonal rings which
are arranged in layers one above the
other one of the carbon carbon bonds is
a double bond
thus the valence of carbon is satisfied
since one electron of each carbon item
in graphite is free to move about
graphite is a good conductor of
electricity the carbon to carbon bond
length is 142 p.m. these layers are held
together by weak force of attraction and
the distance between the layers is a 335
p.m. due to its structure graphite is
not as hard as diamond and is greasy it
is grey in color and is opaque with
metallic lustre Graphite's density
varies from 2 to 2 point to 5 grams per
CC and it melts at about thousand 800
Kelvin we will examine another carbon
allotrope fullerene chemically
fullerenes are formed by the combination
of a large number of carbon atoms the
first one to be identified with c60 its
structure has been established on the
basis of investigations carried out by
Buckminster Fuller an American architect
so fullerenes are often called bucky
balls the shape of fullerene resembles
that of a soccer ball with six member as
well as 5 member rings there are 12 5
member rings and 26 member rings in
fullerene all the carbon atoms are found
to be equivalent and are connected by
both single and double bonds bond length
of single bond is 145 point 3 p.m. bond
length of a double bond is a 338 point 3
p.m.
thanks to remember carbon is represented
by the symbol C its atomic number is 6
that is it contains six protons and six
electrons carbon exists in two forms as
crystalline and amorphous these forms
are known as allotropes of carbon the
crystalline forms of carbon are diamond
graphite and fullerene diamond is the
hardest crystalline form of carbon each
carbon to carbon bond length is 154 PM
graphite is not as hard as diamond and
is a greasy substance the carbon to
carbon bond length is 142 PM fullerene
resembles a soccer ball and has six
membered as well as five membered rings
you