CBSE Class IX SCIENCE CHEMISTRY Is matter around us pure
IS MATTER AROUND US
Matter is a general term for the substance of which all physical
objects are made, however in practice there is no single correct
scientific meaning; each field uses the term in different and often
contradictory ways. Whereas "matter" originally (in Aristotelian
hylomorphism) referred not to an independent thing, but to a co-
dependent "principle," the modern conception is that matter is a
"substance“ that is to say, it exists even apart from
composing something else. Modern science identifies this "substance"
through its physical properties; the most common current definition
of matter is anything that has mass and occupies volume. Matter is
commonly said to exist in four states ( or phases) : solid, liquid,
gas and plasma.
However, advances in experimental technique have realized other
The substances which do not have adulteration are
known as pure substances. Some are given below.
Milk Bread Ghee Jam
A mixture is when two or more different substances are mixed
together but are not combined chemically. The molecules of two or
more different substances are mixed in the form of mechanical
mixtures, solutions, suspensions, and colloids.
While there are no chemical changes to its constituents, the
physical properties of a mixture such as its melting point, may differ
from those of the components. Some mixtures can be separated into
their components by mechanical means.
There are two types of mixtures.
Substances that look the
have one phase and uniform
Example :Alcohol ,wine ,milk
substances in which you can see
more than one color or type of
Heterogeneous substances have
more than one phase and a non-
Example : Sandy water ,
juice with pulp in it sugar
A solution is a homogenous mixture of substances with variable
composition. The substance present in the major proportion is called the
solvent, whereas the substance present in the minor proportion is called the
solute. It is possible to have solutions composed of several solutes. The
process of a solute dissolving in a solute is called dissolution. There are three
types of solution :-Solid, Liquid, Gas.
CHARACTERISTICS OF SOLUTION
A solution is something dissolved in something else. By dissolved it mean it
needs to have some partials ionized a solid you place in water that dissociates
(ions split apart from each other) makes a solution a good solution you can
make in your kitchen is a salt-water solution, Put some regular table salt in a
glass and stir it and you will notice the salt "disappears" what happens is the
sodium ions and the chloride Ions separate and 'hide' between water
Types of solution
• Solid substance
• Fixed volumes,
• Are rigid.
• Cannot be
• Liquid substances
doesn’t have definite
• Definite volume,
are Non -rigid.
• Cannot be
• No definite shape.
• No definite
Are not at all
• Can be easily
•A solution is a homogeneous mixture. The particles of a solution are
smaller then 1nm in diameter, so they cannot be seen with naked eye.
•Because of very small particle size, they do not scatter a beam of light
passing through the solution. So, the path of the light is not visible in the
solution.The solute particles cannot be separated from the mixture by
the process of filtration. The solute particles do not settle down when
left undisturbed. That is, a solution is stable.Many reactions do not
occur until the solid reactants are dissolved to make a solution.The
solvent is present in greater amount in greater amount.
The component of the
solution that dissolves the
other component in it (usually
the component present in
larger amount) is called the
Present on a greater
proportion in the solution.
Solution may or may not be in
the same state of matter as the
The component of the
that is dissolved in the solvent
(usually the component
present in lesser quantity ) is
Present in lesser proportion
in the solution.
Medium of dispersion
Solution will be in the same
state of matter as the solute.
The concentration of a solution refers to the strength of the solution.
Concentration = quantity of solute
quantity of solution (not solvent)
There are 3 basic ways to express concentration:
2) very low concentrations,
3) molar concentrations
1) Percentage (%) concentration can be in V/V, W/W, or W/V
2)Expressing concentrations in parts per million (ppm) requires the
top to be 1,000,000 times smaller than the unit on the bottom.
3) Molar concentration is the most commonly used in
chemistry. Ensure that units are mol/L.
A suspension is a heterogeneous fluid containing solid particles
that are sufficiently large for sedimentation. Usually they must be
larger than 1 micrometer. The internal phase (solid) is dispersed
throughout the external phase (fluid) through mechanical agitation,
with the use of certain excipients or suspending agents. Unlike
colloids, suspensions will eventually settle. An example of a
suspension would be sand in water. The suspended particles are
visible under a microscope and will settle over time if left
undisturbed. This distinguishes a suspension from a colloid, in
which the suspended particles are smaller and do not settle.
Colloids and suspensions are different from solutions, in which the
dissolved substance (solute) does not exist as a solid, and solvent
and solute are homogeneously mixed.
The particles of suspension can be seen by the naked eye.
The particles of a suspension scatter a beam of light passing
through it and makes its path visible
The solute particles settle down when a suspension is left
undisturbed, that is, a suspension is unstable
colloid is a type of mixture in which one substance is dispersed
evenly throughout another. A colloidal system consists of two
separate phases: a dispersed phase (or internal phase) and
a continuous phase . A colloidal system may be solid, liquid, or
Many familiar substances are colloids, as shown in
the chart below. As well as these naturally occurring colloids,
modern chemical process industries utilize high shear mixing
technology to create novel colloids.
Some colloids are translucent because of the Tyndall effect,
which is the scattering of light by particles in the colloid. Other
colloids may be opaque or have a slight color.
There are many types of colloids :-
Aerosol(gas +liquid/solid e.g. fog and smoke)
Foam(liquid +gas e.g. whipped cream)
Emulsion(liquid +liquid e.g. milk)
Sol(liquid + solid e.g. paint)
Solid foam(solid + gas e.g. marshmallow)
Solid emulsion(solid + liquid, e.g. cheese)
Solid Sol(solid + solid e.g. pearl.)
By a colloidal solution one understands a solution, in which
the solved particles are present in such a small grain size that
they cannot be separated by filtration. The solved particles are
larger than molecules, but they are smaller than fillers
in suspensions. Therefore these colloidal solutions behave partly
like genuine solutions. In order to keep such colloidal solutions
stable and to prevent precipitations, wetting and dispersing
agents as well as other additives are added. In
foundries, colloidal graphite solutions are used as die coatings.
One property of colloid systems that distinguishes them from
true solutions is that colloidal particles scatter light. If a beam of
light, passes through a colloid, the light is reflected by the
colloidal particles and the path of the light can i.e., be observed.
A colloid is a heterogeneous mixture.
The size of particles of a colloid is too small to be individually
seen by naked eye.
Colloids do not settle down when left un disturbed, that is, a
colloid is quite unstable.
Common examples of colloids
Fog, clouds, mist
Smoke, automobile exhaust
Milk, face cream
Milk of magnesia, mud
Foam, rubber, sponge, Pumice
Jelly, cheese, butter
Coloured gem stone,glass
A pure substance is a substance where there is only one kind
of matter present and only one kind of particles. Where as a
mixture is an impure substance that has two or more kinds of
matter present and two or more kinds of particles present. Also
a pure substance has fixed, sharp melting and boiling points
and a mixtures varies.
Substance consisting of atoms which all have the same number of
protons – i.e. the same atomic number. Elements are chemically the
simplest substances and hence cannot be broken down further using
chemical methods. At 75 percent, hydrogen is the most abundant
element in the universe, followed by helium at 23 percent and
oxygen at 1 percent. The other elements make up the remaining
1percent. In the earth's crust, oxygen (47 %) is the most abundant
element, followed by silicon (28 %) and aluminum (8 %).
1% Elements in the universe
In chemistry, a compound is a substance that results from a
combination of two or more different chemical element s, in such a
way that the atoms of the different elements are held together by
chemical bonds that are difficult to break. These bonds form as a
result of the sharing or exchange of electron s among the atoms. The
smallest unbreakable unit of a compound is called a molecule.
IONIC COMPOUNDS MOLECULAR COMPOUNDS
Ionic compounds are formed
when metallic elements from
The left-hand side of the
Periodic Table react with
non metallic elements from the
right-hand side of the
Table. Ionic compounds have
high melting and boiling
points. Many ionic compounds
are soluble in water.
Molecular compounds form ed
when two or more nonmetal atoms
form units that are called
molecules. Molecular compounds
generally have low melting and
boiling points. Molecular
compounds do not conduct
electricity in the solid form or in
the liquid form. Some molecular
compounds dissolve in water and
some do not.
A mixture is when two or more
different substances are mixed
together but are not combined
chemically. The molecules of two
or more different substances are
Mixed In the form of mechanical
mixtures, solutions, suspensions,
and colloids. While there are no
chemical changes to its constituents,
the physical properties of a mixture
such as its melting point, may differ
from those of the components.
In chemistry, a compound is a
substance that results from a
combination of two or more
different chemical element s, in
such a way that the atom s of the
different elements are held
together by chemical bonds that
are difficult to break. These
form as a result of the sharing or
exchange of electron s among the
atoms. The smallest unbreakable
unit of a compound is called a
Alloys are mixture of two or
more metals or a non metal
and cannot be separated
into their components by
physical methods. But still, an
alloy is considered as
a mixture because it shows
properties of its constituents
and can have variable
composition. For example,
brass is a mixture of
approximately 30% zinc and
The number of elements known
at present are more than Hundred.
Ninety-two elements are naturally
Occurring and the rest are man-
Majority of elements are solid.
Eleven elements are in gaseous
state at room temperature.
Two elements are liquid at room
Temperature – mercury and Bromine.
Elements, gallium and cesium
become liquid at a temperature
slightly above room temperature