Notes of Ch 2 Is Matter Around us Pure| Class 9th Science I by KNOWLEDGE CAVE I Part 1

                      CHAPTER 2

           IS MATTER AROUND US PURE ?

BY   KNOWLEDGE CAVE

(1)BUT DO WE ACTUALLY KNOW WHAT IS PURITY ?

(1) PURE SUBSTANCE:- It is a substance that is up of a single type of particles.   for example:- Iron,silver,oxygen,sulpher,etc.

  But it not that a substance has to be made of single type of particles only.It can be made up of two or more different kinds of particles also.  LIKE:-Sodium chlorine,carbon dioxide,etc.

(2) CHARACTERISTICS OF PURE SUBSTANCE.

 * It has uniform composition(homogenous).

 * It can't be separated into its constituents.(PHYSICAL METHOD)

* It has fixed melting and boiling point.

* It always possess some characteristics properties.

* Pure substance:-Elements,compounds,etc.

* Impure substance :- Mixtures ,etc.

* Elements:- Are those substances that can't be broken into more simple substance.

 for example :- sulphur sodium,etc.

(2) CHARACTERISTICS OF ELEMENTS =

(1) They are made up of atoms.

(2) Physical & chemical properties of elements are some as of their atoms.

(3) They occur in nature in free or combined form.

(4) They can be prepared artificially by nuclear reactions.

(5) They can be solids,liquids (only 3),gases(11) at room temperature.

* METAL:- re those which have tendency to loose electrons and from respective cat ion.    Na-e-na+(Cat ion).

(3) PHYSICAL PROPERTIES 

* They are malleable. for example =AL,Ag,(Except alkali metals).

* They are ductile. for example =AL,Ag,etc.

* They are lustrous (except Na&k).

* High melting and boiling points(except Na,k (a-melting and boiling points)Sonorous.

(4) CHEMICAL PROPERTIES

(1) Reaction with oxygen 

they react with oxygen to form their respective oxides.

M+water =metal oxides.

Metal oxides:-They are basic in nature, they turn red litmus to blue.

* Some metal oxides are Amphotoeric (acidic & basic in nature) for example:-Al2O3& ZnO

(5) REACTION WITH DILUTE ACIDS

Metal react with dilute acid to give salt and Hydrogen gas.

Metal+dilute acid-metal salt hydrogen gas.

* Non metals:-Are those that always gain electrons and form anions.

(1) PHYSICAL PROPERTIES OF NON METAL 

*They are liquid or gases (one liquid - bromine),C,S,P,I (solid) and rest are gases.

* Non malleable & Ductile as they are brittle.

* Bad conductor of heat and electricity (graphite).

*Have low melting point,Boiling point.(except B,C)

* Non lustrous (except graphite & iodine)

*Non sonorous.

 (2) CHEMICAL PROPERTIES .

REACTION WITH OXYGEN 

* They react with water to form non metal oxide.

*N+Water=non metal oxide.

*Non metal oxides are acidic in nature they turn blue litmus red.

* Reaction with dilute acids 

non metal do not react dilute acids:They don't have sufficient electrons.

(6)  METALLOIDS:-Which have properties similar to non metals.  for example - Si,Ge,etc.

NOBLE GASES:-Are those which are stable as they have stable cofiguration.

for example - He,Ne,Ar,Kr,Xe,Rn,etc.

* COMPOUNDS :- They are formed when 2 or more elements combine in fixed whole number ration.   for example = hydrogen&salt,etc.

(1) CHARACTERISTICS -

* They are homogenous.

* Properties of compounds are entirely different from constituents.

* Constituents can't be separated by physical method.

* Fixed properties like melting point & boiling point.

* Formation of compounds is accompanied by energy changes.   for example - H2O,NaCL,CO2,SO2,etc.

(2) MIXTURES:-IT IS FORMED WHEN TWO OR MORE SUBSTANCES ARE SIMPLY MIXED.

* Homogenous or heterogenous.

* Properties are some as of contituents can be separate by physical methods.

* It is formation does not require or release energy.

* Properties like melting point & Boiling point are not fixed.

IF YOU HAVE ANY TYPE OF QUERY ABOUT THIS CHAPTER I'LL MAKE THREE PARTS OF THIS CHAPTER IT WILL HELP YOU TO UNDERSTAND ABOUT MATTER OTHER WISE YOU CAN CONTACT ME ON knowledgecave1@gmail.com I WILL EXPLAINE YOU IN BRIEF.