Classification of matter - Class 11 PDF Download

Matter is defined as anything that occupies space and possesses mass.
Classification of matter

1)Physical classification

a)Solid

b)liquid

c)Gases

Vapours represent a gaseous state of a substance which is liquid at room temperature.

A substance which is in gaseous state at room temperature is called a gas.

For Ex: Ammonia is a gas but on heating water forms vapours.

2) Chemical classification

All kinds of matter are classified into two types:

a) Homogeneous

b) Heterogeneous

Material is said to be homogeneous if it has uniform composition and identical properties throughout Or a material is said to be homogeneous if it consist of only one phase.

A material is said to be heterogeneous if it consists of a number of phases.The different phases are separated from each other by distinct boundaries.

A pure substance is one which is made up of only one kind of particles(atoms or molecules).

Pure substance are of two types:

1)Elements

2)Compounds

A mixture is one which contains two or more different kinds of particles(atoms or molecules).

Mixtures are of two types:

1)Homogenous mixture

2)Heterogeneous mixture

Elements

An element is usually defined as the simplest form of a pure substance with definite physical and chemical properties and which can neither be broken into nor built from simpler substances by any chemical or physical method.

An element contains only one kind of particles.These particles may be atoms or molecules.

For example: carbon ,sulphur, iron ,gold ,hydrogen ,oxygen ,nitrogen ,silver etc.

The number of elements known to date is 114 .out of these 92 occur in nature in the earth crust and the remaining have been prepared artificially in the laboratory through reactions.

Types of elements

1)Metals

2)Non metals

3)Metalloids

Metalloids
The elements whose properties are intermediate between those of metals and non-metals are known as metalloids.

For Ex:Silicon,Germanium,Arsenic,Tellurium.

Compounds

Compounds are pure substances containing more than one kind of element or atom.

In compounds the two elements are in a fixed proportion by mass and which can be decomposed into its constituent elements by suitable chemical methods. The properties of a compound are completely different from those of its constituent elements.

For example : Water is a compound containing hydrogen and oxygen combined together in a fixed proportion of 1:8 by weight.

It can be decomposed into its constituent elements hydrogen and oxygen by passing electricity through water. Water are completely different from its constituent hydrogen and oxygen.

For Ex:Carbon dioxide ,Sulphur Dioxide ,hydrochloric acid, nitric acid ,washing soda ,common salt are examples of compounds.

Types of compounds

All the compounds may be divided into two categories :

1)organic compounds are the compounds containing carbon and few other elements like carbon , Hydrogen ,oxygen ,nitrogen ,sulphur, halogens. They were originally obtained only from plants and animals.

2)Inorganic compounds are the compounds containing any two or more elements out of more than one 114 elements known.

Mixtures

A material containing two or more substances in any proportion is called a mixture. The properties of a mixture are the properties of its constituents.A mixture can be separated into its constituent by simple physical method.

Types of mixture

1)Homogeneous

2)Heterogeneous

Difference between mixture and compound

Atom

An atom is the smallest particle of an element which may or may not be capable of independent existence.

For example :Atoms of iron ,copper ,Silver ,Gold can exist freely whereas atoms of hydrogen ,oxygen, nitrogen cannot exist freely.

Molecule

A molecule is the smallest particle of an element or a compound which can exist freely.

Molecules may be classified into two categories:

1) Molecules of elements: They are made up of only one kind of atom ,they are called homoatomic or homonuclear molecules.

The atomicity of metal elements like sodium,magnesium,aluminum,copper,iron etc is taken as 1.
They are called as Monoatomic molecules.

2) Hydrogen,Nitrogen,Oxygen,Chlorine,bromine etc have two atoms in their molecules.So the atomicity is 2.They are called as diatomic molecules.

3) Ozone has 3 atoms in its molecules,so the atomicity is 3.They are called as triatomic molecules.

4) Phosphorus has 4 atoms in its molecules,so the atomicity is 4.they are called as tetra-atomic molecules.

Molecules of compounds :They are made up of atoms of different elements and hence are called heteroatomic or heteronuclear molecules.

They may be diatomic ,triatomic depending upon the number of atoms present in a molecule of the compound .

For Ex: HCl, water, carbon dioxide, ammonia, methane etc.