CLASS 9 MATTER AROUND US PURE
Ch-2 Matter around us pure
❆ Common person→ pure means having no adulteration.
❆ Scientist → Mixtures of different substances
Eg :- Common person → pure
Scientist → Impure
According to scientists : A pure Substance consists of a single type of
particles.
Eg :- Sugar, Salt, gold, silver etc.
❆ Characteristics of Pure Substance
• A pure Substance is a homogeneous
• A pure Substance cannot be separated into other kinds of Matter by any
physical process.
• It has fixed melting point one boiling point.
❆ Elements :
• Element term is given by Robert Boyle in 1661.
• Definition given by French chemist → Antoine Laurent Lavoisx
• “A basic form of matter that cannot be broken down into simpler Substance by Chemical reaction is called element.”
Eg :- Sulphur, Sodium, etc.
Total element :- 118
92 Rest are (26)
are natural man-made
❆ States of Elements
• Solid state elements :- Iron, copper, aluminium, silver, gold, sodium etc.
• Liquid state elements :- Mercury and Bromine
• Gaseous state elements :- Hydrozen, oxygen, Nitrogen, Chlorine etc.
Element
Metals Non-metals Metallaids
Metals
Properties of metals (Physical)
• Metals are malleable
↓
=> Metals can be hammered or beatean to form thin Sheets without
breaking.
↓
=> Gold and silver are the mast malleable
↓
=> Also Aluminium, copper and iron
Exception : Alkali metals
• Metals are ductile
=> Metals can be drawn or stretched into thin wires
=> Gold, silver, copper and aluminium are most ductile.
• Metals are good conductor of heat and electricity.
=> Silver is best conductor of heat.
• Metals are lustrous (Shining surface)
• Metals are generally hard.
Exception: Na, K
• Metals are generally have high melting and boiling points
Exception: Na, K, Ca
• Metals have silver and grey colour.
Exception: gold, copper
• Metals are sonorous
• Metals make a ringing sound when hit.
Non-metals
Physical properties of non-metal
• They display a variety of colours.
• They are poor conductor of head and electricity.
Exception: graphite
• They are not lustrous, sonorous or ductile, malleable. (They are brittle)
Exception: Graphite and Iodine.
• Having low melting paint and boiling point
Exception: B, C
Metalloids
• Elements having intermediate properties between
those of metal and non-metals are called metalloids.
Eg: Silicon, boron, germanium etc.
Compound
• A compound is a substance composed of two or more elements, chemically combined with one another in a fixed proportion.
Eg: H₂O → Hydrogen and oxygen
Chemically combined together
CO₂ NaCl CaCO₃
↓ ↓ ↓
Carbon + oxygen Sodium + Chloride Calcium + Carbon
+ oxygen
Characteristic of Compound
Homogeneous
• It’s property of compound are entirely different from constituents:
Eg → H2O → oxygen → different property
↓
Hydrogen → different property
• Constituent can't be separated by Physical method.
• Fixed properties like melting point and boiling point.
• Formation of compound is accompanied by energy change.
Impure Substance (Mixture)
• It is formed when two or more substance are simply mixed.
Types of Mixture
Homogeneous Heterogeneous
Mixture Mixture
• Homogeneous Mixture
A mixture in which the constituents are uniformly distributed throughout, without any clear boundaries of separating is called Homogeneous mixture.
Eg → Salt solution, Sugar Solution, air etc.
• Heterogeneous Mixture
A mixture that does not have uniform composition, has visible
boundaries of separation between its constituents is called
heterogeneous mixture. Eg:- Salt and Sand mixture, polluted water
Solution
It is homogeneous mixture of two or more substances. The component of mixture can be two, three, four or more
Eg:- Lemon Juice
Common type of Mixture are -> Binary Solution
Binary solution -> The solution with two components:
(i) Solute -> small amount - it gets dissolved
(ii) solvent -> large amount - it dissolve solute
Eg:- Salt + water
↓ ↓
Solute Solvent
• Solute :- constituent present in less amount and it dissolves.
• Solvent :- constituent present in more amount and in it
solute get dissolved.
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