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Is Matter Around Us Pure? Cheat Sheet (DRAFT) by

Chemistry chapter 2 of NCERT + information from Dinesh class 9 super simplified chemistry

This is a draft cheat sheet. It is a work in progress and is not finished yet.

Pure Substances

a single substance or matter which cannot be separated into other kinds of matter by any physical changes
There are two types of pure substances elements and compounds
ELEMENTS = pure substance made up of one type of atoms only
COMPOUNDS = pure substance containing two or more types of elements which are combined together in a fixed proportion by mass

Elements

SOLID ELEMENTS = copper silver gold potassium carbon­(di­amond and graphite) iodine phosphorus etc
LIQUID ELEMENTS = only mercury and bromine exist at room temper­ature. Gallium and Cesium become liquids at a temper­ature of 302K and 303K. These are slightly higher than the room temper­ature 298K.
GAESEOUS ELEMENTS = eleven elements exist in gaseous state at room temper­ature. These are hydrogen oxygen chlorine fluorine helium argon neon nitrogen xenon krypton and radon

Metals

Metals are solid at room temper­ature
mercury is liquid at room temper­ature. Gallium and Cesium become liquid at temper­ature slightly above the room temper­ature
The atoms are very closely packed in space. This arrang­ement is known as crystal lattice. Lattice varies from metal to metal.
Metals have shiny surfaces. they generally have silver­-grey or golden­-yellow surfaces. This property is known as lustre.
Metals are good conductor of heat and electr­icity.
Copper and aluminium
Metals are generally quite hard
Potassium and sodium
Metals are malleable
Metals are ductile
Metals are sonorous
Metals generally have high melting and boiling points

Non-Metals

are either gases or solids at room temper­ature
bromine
vary in colour. solids have dull surfaces
*crystals of iodine
mostly poor conductors of heat and electr­icity
Graphite
Most of them are quite soft and have less densities than metals
diamond
non malleable and non ductile in nature
have very low melting and boiling points

Compounds

Inorganic compounds = have been obtained from non living sources such as rocks and minerals
common salt marble washing soda baking soda carbon dioxide ammonia etc
Organic compounds = obtained from living beings such as plants and animals. contain carbon as their essential component. also called carbon compounds
methane ethane propane alcohol sugar proteins oils fats etc
Acids
Sulphuric acid, hydroc­holoric acid and nitric acids
Bases
Sodium hydroxide, Potassium hydroxide and calcium hydroxide
Salts
sodium chloride, calcium nitrate and zinc sulphate

Compounds Properties

composed of the same elements combined in a fixed ratio by mass to form molecules
a pure compound is homoge­neous in nature
a chemical compound is formed as a result of chemical reaction between consti­tuent elements
properties of a compound are different from the elements from with which it is formed
consti­tuents of a chemical compound cannot be separated mechan­ically
formation or decomp­osition of compounds involves energy changes
 

Physical change

brings change in the physical state of matter under suitable conditions
Properties
changes the interp­article forces or the interp­article spaces
 
no change in the compos­ition of the substances
 
donot change their main charec­ter­isitcs
 
no new substance is formed
 
change is temporary and can be reversed by reversing the conditions which bring about the change
 
no energy change generally occurs during a physical change

Chemical change

brings a change in the chemical compos­ition of the matter
generally there is an exchange in consti­tuents and new substances are formed
Properties
Physical state of the substance may or may not change
 
always a change in the physical compos­ition of the substances undergoing chemical changes
 
change in the charac­ter­istics of the substance involved
 
new substance is always formed
 
chemical changes are permanent in nature and cannot be easily changed
 
energy reactions always occur in chemical reactions respon­sible for these changes

Chemical change

brings a change in the chemical compos­ition of the matter
generally there is an exchange in consti­tuents and new substances are formed
Properties
Physical state of the substance may or may not change

Chemical change

brings a change in the chemical compos­ition of the matter
generally there is an exchange in consti­tuents and new substances are formed
Properties
Physical state of the substance may or may not change
 

Solutions

a homogenous mixture of two or more non reacting substances
Types of solution:
Solid solution
solid acts as the solvent
Liquid solution
liquid acts as the solvent
Gaseous solution
gas acts as the solvent
Only a mixture of miscible liquids is a solution. In case, they do not mix with each other and form separate layers they are known as emulsion
in the homogenous mixture, the particle size is 1nm in diameter
alloys are homogenous mixture of two or more metals or non metals
Examples of solution
sugar in water
 
iodine in alcohol
 
aerated drinks
 
air
 
copper sulphate in water
 
dilute hydroc­hloric acid
 
brass
 
bronze
 
solder

Properties of a solution

homogenous in nature
all components are present in the same phase
particles cannot be seen by naked eye or ordinary microscope
solution particles can pass through the fine pores of the filter paper
the components do not settle down if left undist­urbed for a very long time. this shows that a solution is quite stable in nature
particles do not scatter a beam of light
a saturated solution becomes unsatu­rated upon heating
a solution in which water acts as the solvent it is known as aqueous solution while the solution in which the solvent is another liquid it is non aqueous solution

Saturated solution

a solution becomes saturated if the solute starts separating at the bottom of the container in which the solution is being prepared at a given temper­ature
a saturated solution becomes super saturated upon cooling

Suspen­sions and Colloidal Solutions

a hetero­genous mixture in which the solid particles are spread throughout the liquid without dissolving in it. they settle as precip­itate of if the suspension is left undist­urbed for a while
Properties
hetero­genous nature
 
particle size is more than 100nm
 
particles can be seen with naked eyes
 
solid particles can be easily separated through ordinary filter papers
 
particles are unstable as they settle down if the suspension is left undist­urbed. this is known as precip­itate

Colloidal Solutions

hetero­genous in nature but have smaller size of particles which are undist­ributed .It ranges between 1nm to 100nm
Properties
appear to be homogenous but are hetero­genous
 
are a two phase system
 
particles pass through ordinary filter papers
 
particles carry charge
 
particles follow a zig-zag path
the scattering of the beam of light by the dispersed phase of particles is known as Tyndall effect
scatters the beam of light passing through it
 
colloidal solutions in which only liquids partic­ipate are known as emulsions
 

Mixtures

the combin­ation of two or more substances which are physically mixed and are not chemically combined with each other and may be also present in any propor­tions
Homogenous Mixture
the components are mixed uniformly mixed without any clear boundary of seperation
sodium chloride and sugar in water . Air is a homogenous mixture of gases
Hetero­genous Mixture
the components do not have uniform compos­ition and also have visible boundaries of separation between the consti­tuents
sand and common salt. Oil and water