Understanding matter

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maharashtra board ninth class chapter

maharashtra board ninth class chapter

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  • 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