IS MATTER AROUND US PURE What is pure substance? A pure substance means a single substance which cannot be separated into other kinds of matter by any physical process. e.g. copper, silver, sodium chloride, potassium nitrate, etc.

Types of pure substances Elements: An element is the simplest or basic form of a pure substance which cannot be broken into anything simpler than it by physical or chemical methods. The pure substance which is made up of one kind of atoms only. Types of elements based on characteristics. Metals and Non-metals There are nearly 118 present in this world. And 92 of the occur from nature and rest are man made.

Property Metals Non-metals 1. State of existence Metals are solids at room temperature. (Exception: Mercury is a liquid at room temperature) Non-metals exist in all the three states of matter. 2. Lustre Metals have shining surfaces i.e., lustre. These are normally non-lustrous (Exception: Crystals of iodine have bright lustre) 3. Conductivity Metals are good conductor of heat and electricity. Non-metals are poor conductor of heat and electricity. (Exception : Graphite is a good conductor of electricity.) 4. Density The density of metal is quite high. The density of non-metal is low. 5. Hardness Metals are usually very hard. (Exception : Na and K are quite soft). Non-metals are normally soft. (Exception : Diamond is the hardest substance known). 6. Sonorosity Metals are sonorous which means that they produce sound when struck with some hard object. Non-metals are non- sonorous. No sound is noticed in their case. 7. Malleability & ductility Metals are malleable and ductile. Non-metals are not malleable and ductile. These are brittle 8. M.P. and B.P. Metals have normally high m.p. and b.p. The m.p. and b.p. of non-metals are usually low.

COMPOUNDS OR CHEMICAL COMPOUNDS A pure substance containing of two or more elements which are combined together in a fixed proportion by mass. Types of compounds : Organic and Inorganic Characteristics of compounds : Composed of same elements combined in a fixed ratio by mass. Homogeneous in nature. Formed as a result of chemical reaction. Properties are different. Constituents cannot be separated. Formation involves energy.

MIXTURES OR IMPURE SUBSTANCES The combination of two or more substances (elements or compounds) which are physically mixed and are not chemically combined with each other and may also be present in any proportion. Types of mixtures : Homogeneous and heterogeneous mixtures Homogeneous Mixtures : A mixture is said to be homogeneous if the different constituents or substances present in it are uniformly mixed without any clear boundary of separation. Heterogeneous Mixtures : A mixture is said to be heterogeneous if it does not have uniform composition throughout the solution.

Solution Suspension Colloidal Solution A solution is a homogeneous mixture of two or more substances. Suspension A suspension is a heterogeneous mixture in which the solute particles do not dissolve but remain suspended throughout the bulk of the medium. Colloidal Solution A collid is a hetereogeneous mixture in which the particles are uniformly spread throughout the solution.

Separating the components of a mixture Evaporation Separation of two immisible liquids

Separation of dyes in black ink using paper chromatography Separation of two immisible liquids by distillation

Separation by sublimation Fractional distillation

separation of components of air