FUNDAMENTAL CONCEPTS
Matter: Anything which occupies space and has mass is called matter.
Classification of matter: On the basis of physical state, matter can be
classified into solids, liquids and gases. On the basis of chemical
constitution matter can be classified into elements, compounds and mixtures.
Solids:
Solids have a fixed shape and fixed volume
Solids cannot be compressed much
Solids are heavy and have high density
Solids are rigid and do not flow.
Liquids:
Liquids have no fixed shape but have fixed volume.
(They take the shape of the container).
Liquids cannot be compressed much.
Liquids have moderate densities. (Comparatively
lesser than solids)
Liquids are fluid and generally flow easily.
Gases:
Gases have neither fixed shape nor fixed volume
(Gases take the shape of container and fill it completely).
Gases have low densities.
Gases are fluid and flow easily.
Elements:
An element is a substance, which cannot be spilt up
into two or more simpler substances by usual chemical methods of applying heat,
light or electric energy.
An element is made up of atoms having same atomic
number.
Compound:
A compound is a substance made
up of two or more elements chemically combined in a fixed proportion by weight.
A compound cannot be separated in to its components
by physical methods.
The properties of a compound are entirely different
from those of its constituent elements.
Energy in the form of heat, light, etc. is usually
given out or absorbed during the formation of the compound.
Compound has a fixed melting point, boiling point,
etc.
Compound is a homogeneous substance.
Mixture:
A mixture is a substance, which consists of
two or more elements or compounds not chemically combined together. The
composition is variable and the constituents can be present in any proportion
by weight.
Mixture can be separated into its constituents by
physical processes like filtration, evaporation, sublimation, distillation,
solvent extraction, magnet, etc.
Mixture shows the properties of constituents
present in it.
A mixture does not have a definite melting or
boiling point.
Energy in the form of heat, light, etc. is not
usually given out or absorbed during the formation of the mixture.
Mixtures can be further classified into homogeneous
and heterogeneous mixtures.
Heterogeneous mixture does not
have uniform composition through out its mass. It has visible boundaries of
separation between the various constituents.
Homogeneous Mixture has uniform
composition through out its mass. It has no visible boundaries of separation
between the various constituents.
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