Introduction - Carbon & its Compounds, Science Video Lecture - Class 10

carbon and its compounds carbon is a
chemical element that has the symbol C
and the atomic number six it has three
isotopes with mass numbers 12 13 and 14
C 14 is radioactive elemental carbon
exists in nature in crystalline as well
as amorphous forms as shown here in
combined forms carbon is present in the
food we eat the clothes we wear the
cosmetics we use in fuels and many of
the drugs and medicines carbon is a
special element because it plays a
dominant role in the chemistry of life
bonding in carbon the covalent bond
covalent bonding is a form of chemical
bonding characterized by the sharing of
one or more pairs of electrons between
two atoms carbon forms compounds mainly
by sharing of electrons the most common
type of covalent bond is the single bond
where one pair of electrons is shared
between two atoms ethane is an example
all bonds with more than one shared pair
are called multiple covalent bonds in a
double bond two pairs of electrons are
shared ethane is an example in a triple
bond three pairs of electrons are shared
teen is an example
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melting points and boiling points of
some compounds of carbon the forces of
attraction between the molecules of a
carbon compound are not very strong so
they have low melting and boiling points
versatile nature of carbon carbon has
the unique ability to form covalent
bonds with other atoms of carbon giving
rise to large molecules this property is
called catenation since carbon has a
valency of 4 it is capable of bonding
with four other atoms of carbon or atoms
of other mono valent elements the bonds
that carbon forms with most other
elements are very strong making these
compounds exceptionally stable
saturated and unsaturated carbon
compounds saturated compounds are
compounds in which carbon atoms are
joined together by single bonds
unsaturated compounds are compounds in
which carbon atoms are joined together
by double or triple bonds in order to
arrive at the structure of simple carbon
compounds the first step is to link the
carbon atoms together with a single bond
and then use the hydrogen atoms to
satisfy the remaining balances of carbon
unsaturated carbon compounds are more
reactive than the saturated carbon
compounds
affinity of carbons with other elements
carbon has a great affinity with
hydrogen carbon also forms bonds with
elements such as halogens oxygen
nitrogen and sulfur in a hydrocarbon
chain one or more hydrogen atoms can be
replaced by these elements such that the
valency of carbon remains satisfied in
such compounds the element replacing
hydrogen is often referred to as hetero
atom these hetero atoms confer special
properties to the compound regardless of
the length and nature of the carbon
chain and hence are called
functional groups
homologous series a series of organic
compounds that have similar structural
features but differ from adjacent
members but ch2 group is referred to as
homologous series each member of
homologous series is called homolog
characteristics of homologous series
observe the schemas shown here
structural formula all the members of
the homologous series have a same
structural formula molecular formula
molecular formula of different members
of a homologous series differs from
previous and next member by ch2 nature
of element all the members of series
have same type of elements functional
group all the members of homologous
series contain same functional group
general formula members of a homologous
series can be represented by a general
formula molecular mass molecular mass of
any two consecutive members differ by 14
units chemical properties all the
members of a homologous series have same
chemical properties due to same
functional group methods of preparation
generally all the members of a series
can be prepared by using same method
physical properties physical properties
of the members of a homologous series
vary with the increase in atomic weight
Naumann claytor of carbon compounds the
names of compounds in a homologous
series are based on the name of the
basic carbon chain modified by a prefix
or suffix indicating the nature of the
functional group
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chemical properties of carbon compounds
chemical properties of carbon compounds
the four important chemical reactions of
carbon are combustion oxidation addition
and substitution
some important carbon compounds ethanol
some important properties and reactions
of ethanol are outlined here read
through to understand
some important carbon compounds ethanoic
acid some important properties and
reactions of ethanoic acid are outlined
here read through to understand
soaps and detergents Serbs are sodium or
potassium salts of fatty acids produced
from the hydrolysis of fats in a
chemical reaction called saponification
detergents are primarily surfactants
which could be produced easily from
petrochemicals surfactants lower the
surface tension of water essentially
making it wetter so that it's less
likely to stick to itself and more
likely to interact with oil and grease
detergents are similar to soap but they
are less likely to form films soap scum
and are not affected by the presence of
mineral in water hard water
formation of Miss Ellis the organic part
of a natural soap is a negatively
charged polar molecule
it's hydrophilic carboxylate group
interacts with water molecules via ion
dipole interactions and hydrogen bonding
the hydrophobic part of a soap molecule
it's long nonpolar hydrocarbon chain
does not interact with water molecules
the hydrocarbon chains are attracted to
each other by dispersion forces and
cluster together forming structure
called Miss Ellis in these miss Ellis
the carboxylate groups form a negatively
charged spherical surface with the
hydrocarbon chains inside the sphere
because they are soap miss Ellis repel
each other and remain dispersed in water
because they are negatively charged
Effects of soap in cleaning those soaps
are excellent cleansers they do have
disadvantages as salts of weak acids
they are converted by mineral acids into
free fatty acids these fatty acids are
less soluble than the sodium or
potassium salts and form a precipitate
or soap scum because of this soaps are
ineffective in acidic water also soaps
form insoluble salts in hard water such
as water containing magnesium calcium or
iron the insoluble salts form bathtub
rings leave films that reduce hair
lustre and rough and textiles utter
repeated washings synthetic detergents
however may be soluble in both acidic
and alkaline solutions and do not form
insoluble precipitates in hard water
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