MATTER

Classification of matter Element Metals and non metals Symbols Molecules Chemical formula Compounds Mixture Formula unit, Formula mass and Molecular mass

CHAPTER NO.2MATTER

The physical material of the universe is called Matter.

OR

Anything having mass and occupies space is called Matter

States of matter

Ordinary matter can exist in three physical states

Solids; Liquids and Gases.

Examples

Silver,Water and Oxygen.

Matter

Pure Substance Mixture(Impure Substance)

Homogeneous HeterogeneousCompounds Elements

Metals Non-metals

Classification of Matter

Ionic Compound

s

MolecularCompounds

PURE SUBSTANCESThe substances which are made up of only onekinds of atoms, ions or molecules are called puresubstances.Pure substances are further classified into1. Element2. Compound

ElementPure substance having all the atoms with same atomicnumber is called an element. OrA substance consisting of chemically identical atoms iscalled an element.Elements have distinct properties of their own and retainthem under all conditions. ExamplesGold is an element and if it is broken down into pieces,

eachpiece will retain the properties of gold, similarly, Iron willremain Iron and Carbon will remain Carbon after division

intosmaller parts.

Classification of Elements

Element

Metals Non-Metals

Those elements whose oxides and hydroxides are basic in nature and possess low I.E., E.N. and

E.A. are called Metals

Metals

PROPERTIES OF METALS They are sonorous, means that they give off a

note when hit. They are malleable and can form sheets. They are ductile and can be drawn into wires. They are good conductors of heat and electricity. They have a relatively high densities. They have great tensile strength and can

withstand stress and strain. They have high melting point and boiling point.

Non-metals Those elements whose oxides are acidic in

nature and possess higher I.E., E.N., and E.A. are called non-metals.

Sulphur Phosphorus

PROPERTIES OF NON-METALS They are non sonorous. They are neither malleable nor ductile. They are poor conductor of heat and electricity. They have relatively low densities. They are usually brittle and break easily when

subjected to stress and strain. Non-metals have low melting point and boiling

point.

SYMBOLAn abbreviation used for the chemical name of

anelement is called symbol.

ORLetter or letters which represent chemical

name of anelement is known as symbol.

RULES GOVERNING SYMBOLS OF ELEMENTS Symbols are composed of one, two or three

letters.

If one letter is used, it is capitalized.

If two or three letters are used, the first is capitalized and the others are lowercase letters.

SOME COMMON ELEMENTS WHOSE SYMBOLS CONSIST OF FIRST LETTER OF THEIR

ENGLISH NAMES Boron Nitrogen Fluorine Sulphur Carbon Oxygen Phosphorus Iodine

B N F S C O P I

SOME COMMON ELEMENTS WHOSE SYMBOLS CONSIST OF TWO LETTERS

OF THEIR NAMES Helium Bromine Bismuth Calcium Beryllium Barium Chlorine Chromium

He Br Bi Ca Be Ba Cl Cr

SOME COMMON ELEMENTS WHOSE SYMBOLS CONSIST OF FIRST AND SECOND LETTERS OF

THEIR LATIN NAMES

English Name Symbol

Potassium Iron Copper Silver Tin Antimony Tungsten Gold Mercury Lead

K Fe Cu Ag Sn Sb W Au Hg Pb

KaliumFerrumCuprumArgentumsStannumStibiumWolframAurumHydrargyrumPlum bum

Latin Name

The smallest particle of a substance which can existindependently as a separate unit and shows all theproperties of that substance is called molecule. ORAtoms of most elements combine with either atoms of

the sameelement or atoms of other elements to form molecules. Types of Molecules on bases of number of atoms:On the bases of number of atoms Molecules may be Mono atomic.(He,Ne and Ar). Diatomic. (H2,O2 and Cl). Triatomic. (H2O,CO2 and H2S). Polyatomic.(CH4,NH3 and C6H6).

Molecule

Molecules

Molecules of Elements

Molecules of Compounds

CLASSIFICATION OF MOLECULES

MOLECULES OF ELEMENTSThe molecule which consists of a fixed number

of one kind of atom chemically combined together is known as molecules of elements

Oxygen Molecule Water Molecule

Nitrogen Molecule

MOLECULES OF COMPOUNDSThe molecule consists of a fixed number of different

kinds of atoms chemically combined together is known as molecule of compound.

Carbon dioxide Molecule Sulphur dioxide Molecule

Water Molecule

CHEMICAL FORMULA The symbolic representation of molecule of

a compound is called chemical formula.

OR The combination of symbols of elements

present In a molecule of a substance is called chemical

formula.

EXAMPLES OF CHEMICAL FORMULA

Oxygen

Hydrogen

Ammonia

Glucose

Water

O2

H2

NH3

C6H12O6

H2O

METHOD OF WRITING A CHEMICAL FORMULA

1) Write the correct symbols of ions side by side. 2) Write the positive ions on left hand side and negative ions on right hand side.

3) Write the valency on the right top side of each ions.

4) Write the polyatomic radicals in brackets.

5)Cross the valencies to the lower right of each radicals.

6) if the valencies are equal then donot cross it.

EXAMPLESWrite the chemical formula for the molecules of thefollowing compounds.1.Magnesium ChlorideStep 1. Magnesium chloride.Step 2. Mg Cl.Step 3. Mg+2 Cl-1

Step 4. Mg+2 Cl-1

Step5. Formula =MgCl2

ALUMINIUM SULPHATE:Step 1. Aluminum sulphate.Step 2. Al SO4

Step 3. Al+3 SO4-2

Step 4. Al+3 SO4-2

Step 5= Al2(SO4)3

IMPORTANCE OF CHEMICAL FORMULAChemical Formula help us to know about:1. Elements present in a molecule.

2.Number of atoms of each element present in a molecule.

3. Composition of the molecule.

Chemical Formula

Empirical Formula Molecular Formula

TYPES OF CHEMICAL FORMULA

Structural Formula

Empirical Formula

The chemical formula which shows simplest ratiobetween the atoms present in a molecule of acompound is called Empirical Formula.Examples

HO is the empirical formula of Hydrogen Peroxide.CH2O is the empirical formula of Glucose.CH is the empirical formula of Benzene.

Note: All Ionic compounds are represented by their Empirical Formula.

MOLECULAR FORMULAThe formula which indicates the actual number ofatoms in a molecule is called molecular formula.

Molecular Formula represents molecular compounds. Example Molecular formula of Benzene is C6H6

STRUCTURAL FORMULA Formula which indicates the arrangement of

atoms and bonds in molecule is called structural formula.

Angular Water Linear Carbon dioxide

Compound

Compound is a pure substance which contains onlyone type of molecule made up of atoms of more oneelement. ORThe pure substance formed by the chemicalcombination of two or more atoms of differentelement in a fixed mass ratio is known as compound. Examplewhen Carbon is burnt in Oxygen, Carbon dioxide isformed.

TYPES OF COMPOUND

Compound

Ionic Compound Molecular Compound

IONIC COMPOUNDThe type of Compound which is formed by thechemical combination of a large number of positiveand negative ions is called Ionic compounds .Ioniccompounds are generally crystalline, like NaCl.

MOLECULAR COMPOUNDA compound that consists of separate, independentunits or molecules, is called a molecular compound.ExamplesWater (H2O), Carbon dioxide(CO2),Benzene(C6H6) and

Glucose (C6H12O6)

MIXTURE An impure substance formed by the physical

combination of two or more pure or impure substances is called mixture.

A mixture consists of two or more substance which are not chemically combined. The substances in a mixture could be all the elements, all compounds or a combination of elements and compounds.

For Example:- Air is a mixture because it is composed of many gases like Nitrogen, Oxygen, Carbon dioxide and inert gases which are combined physically and are not in a fixed mass ratio.

Mixture

Homogeneous MixtureHeterogeneous Mixture

TYPES OF MIXTURE

HOMOGENEOUS MIXTURES Mixtures having uniform composition throughout

are called homogeneous mixtures. Examples Air, Steel, Salt, Sugar and water solution.

HETROGENEOUS MIXTURE The mixtures which have different composition

throughout its mass is called heterogeneous mixture.

Examples Rocks, Soils and Ice-Cream etc….

DIFFERENCES BETWEEN COMPOUNDS AND MIXTURES

Compound Mixture

1. It is a pure substance.

2. It is formed by chemical combination.

3.Its composition Is fixed.

4.The combining substances lose their properties.

1. It is an impure

substance.2. It is formed by

Physical combination.

3. Its composition is variable.

4. The combining substances doesn’t lose their properties.

DIFFERENCES BETWEEN COMPOUNDS AND MIXTURES

Compound Mixture

5. It can’t be separated by any physical method.

6. Examples: Glucose, Water and Carbon dioxide gas etc…..

5. It can be separated by simple physical method.

6. Examples: Air, Rocks, Sugar solution etc…..

FORMULA UNIT The smallest repeating unit of an ionic compound is

called Formula unit.Example: NaCl indicates a formula unit, it can’t exist independently.

In case of molecular compound, it may or may not exist independently. Example: H2O, NH3, CH4……. are the formula units exist independently. Here the formula unit and molecules of there compounds are the same.On the other hand, CH(from C6H6), CH2O(from C6H12O6), NaCl…… can’t exist independently. Therefore, they aren’t called molecules but they are called Empirical Formula.

Formula unit is used for Ionic and Empirical formula is used for Covalent compounds.

C C C

C C C

H

H

H

H

H

H

Benzene molecule

Empirical Formula

Emperical formula

[NaCl] is the FORMULA UNIT

MOLECULAR MASS The sum of atomic masses of all the atoms present in

one molecule of a substance is called molecular mass. Examples

Molecular mass of Benzene C6H6 = 6 × 12 + 6 = 78

Molecular mass of Glucose C6H12O6=6×12+12+6×16=180

Molecular mass of Carbon dioxide CO2 = 12+ 2×16 = 44

Molecular mass of Water H2O = 2 + 16 = 18

Note: The following points are important for finding molecular mass of a substance.

1) Correct chemical formula of the molecule. 2) Number of atoms of each element in a given molecule. 3) Atomic number of all atoms present in a molcule.

FORMULA MASSIt is the sum of atomic masses of all the atoms

present in a formula unit or E.FExamples 1)Formula mass of Benzene( CH) = 12 + 1 =13 2)Formula mass of NaCl = 23 + 35.5 = 58.5