maharashtra board ninth class chapter

1. UNDERSTANDING MATTER

2.  T h e r e i s g a p b e t w e e n t h e p a r t i c l e s o f m a t t e r .
 M a t t e r i s s o m e t h i n g t h a t o c c u p i e s s p a c e a n d h a s m a s s .
 M a t t e r i s m a d e u p o n s m a l l p a r t i c l e s .
 P a r t i c l e s o f m a t t e r a r e h e l d t o g e t h e r b y a c h e m i c a l b o n d .
 E v e r y p a r t i c l e o f m a t t e r h a s t h e s a m e p r o p e r t i e s .
 P a r t i c l e s o f m a t t e r a r e i n c o n s t a n t m o t i o n .
MATTER

3. A pure substance has a definite and constant composition — like salt or sugar.
PURE SUBSTANCES
When substances change state, it is because the spacing between the particles of the
substances is changing due to a gain or loss of energy.

4. ELEMENTS
consists of only one kind of atom,
cannot be broken down into a simpler type of matter by either
physical or chemical means, and
can exist as either atoms (e.g. argon) or molecules (e.g., nitrogen).
An element can be represeneted by using symbol.

5. Atomic
Number
(z)
Name Symbol
1 hydrogen H
2 helium He
3 lithium Li
4 beryllium Be
5 boron B
6 carbon C
7 nitrogen N
8 oxygen O
9 fluorine F
10 neon Ne
ELEMENTS

6. CLASSIFICATION ELEMENTS
METALS METALLOIDSNON METALS
 A class of 8 elements that have
properties of both metals and nonmetals.
B , Si , Ge , As , Sb ,Te , Po , At
 appears lustrous, but is not malleable or
ductile (it is brittle - a characteristic of
some nonmetals).
 It is a much poorer conductor of heat
and electricity than the metals.
 Metalloids are useful in the
semiconductor industry.
 Metallic luster (shine)
 Generally solids at room
temperature
 Malleable
 Ductile
 Conduct heat and electricity
 Exist as extended planes of
atoms
 Combine with other metals to
form alloys which have
metallic characteristics
 Form positive ions, e.g. Na+,
Mg2+, and Al3+
 Rarely have metallic luster
(shine)
 Generally gases at room
temperature
 Neither malleable nor ductile
 Poor conductors of heat and
electricity
 Usually exist as molecules in
thier elemental form
 Combine with other
nonmetals to form covalent
 Generally form negative ions,
e.g. Cl-, SO4
2-, and N3-

7. METALS

8. NON METALS

9. METALLOIDS

10. Compounds
Many compounds contain hydrogen and oxygen, but only one has that special 2 : 1 ratio we call
water. The compound water has physical and chemical properties different from both hydrogen
and oxygen — water’s properties are a unique combination of the two elements.
Compounds are pure substances.
They are made up of two or more elements combined chemically.
The constituents of a compound are present in a fixed ratio.
Compounds have fixed properties. For example, a particular compound will have fixed
temperatures at which it melts and boils.
A compound can have properties different from its constituents, as a new substance is formed
when the constituents are chemically combined.
The constituents of a compound can be separated only by chemical methods.

11. Compounds examples

12.  Mixtures are physical combinations of pure substances that have no definite or constant composition — the
composition of a mixture varies according to who prepares the mixture.
 Although chemists have a difficult time separating compounds into their specific elements, the different parts
of a mixture can be easily separated by physical means, such as filtration.
Mixtures
 Mixtures are impure substances.
 They are made up of two or more substances mixed physically.
 The constituents of a mixture are present in varying ratios.
 Mixtures do not have fixed properties. Their properties depend on the nature of their components and the
ratios in which they are combined.
 In mixtures, no new substance is formed. The properties of a mixture are the same as the properties of its
constituents.
 The constituents of a mixture can be separated easily by physical methods.

13. Mixtures examples

14. A homogeneous mixture, sometimes called a solution, is relatively uniform in
composition; every portion of the mixture is like every other portion.
For example, if you dissolve sugar in water and mix it really well, your mixture is
basically the same no matter where you sample it.
Mixtures can be either homogeneous or heterogeneous:
A heterogeneous mixture is a mixture whose composition varies from position to
position within the sample.
For example, if you put some sugar in a jar, add some sand, and then give the jar
a couple of shakes, your mixture doesn’t have the same composition throughout
the jar. Because the sand is heavier, there’s probably more sand at the bottom of
the jar and more sugar at the top.

15. A solution is always transparent, light passes through with no scattering from solute particles which are molecule in
size. The solution is homogeneous and does not settle out. A solution cannot be filtered but can be separated using
the process of distillation.
solution
Gas Liquid Solid
Gas Oxygen and
other gases in
nitrogen (air)
Water vapor in air (humidity)
The odor of a solid -- molecules of that
solid being dissolved in the air
Liquid Carbon dioxide in
water
(carbonated
water)
Ethanol (common alcohol) in
water; various hydrocarbons in
each other (petroleum) *
Sucrose (table sugar) in water; sodium
chloride (table salt) in water
Solid Hydrogen
dissolved to
palladium
Water in activated charcoal Steel, Brass, other metal alloys

16.  The substance in which solute dissolved is solvent.
 The substance which is dissolve is called solute.
o The complete dissolution of one liquid in another liquid is
called “miscibility”. An example of this would be vinegar
and water. When the opposite occurs, the substances are
called “immiscible” – an example is oil and water.
o Solutions are simply mixtures of materials, one of which is
a liquid or a gas. The liquid or gas, also called a fluid
because it is able to flow, serves as the “solvent”. The
other material in the solution is called the “solute”.
o The process of combining the solute and the solvent can
also be called “dissolving” the solute in the solvent. The
ability to dissolve is called “solubility”.

17.  A suspension is cloudy and heterogeneous mixtures in which the solute particles
do not dissolve but remains suspended in it.
 These particles are visible to the naked eyes
suspension

18.  A colloid is intermediate between a solution and a suspension. While a suspension will separate out a
colloid will not.
 Colloids can be distinguished from solutions using the Tyndall effect.
 Light passing through a colloidal dispersion, such as smoky or foggy air, will be reflected by the larger
particles and the light beam will be visible.
colloid
A colloid is a type of mixture intermediate between a homogeneous mixture (also called a solution) and
a heterogeneous mixture with properties also intermediate between the two.

19. Tyndall effect.

20. MATTER
Mixtures
METALS METALLOIDS
NON METALS
Heterogeneous
mixture
Homogeneous
mixture
suspension colloidsolution