Some Basic concepts of chemistry

 Chemistry :-

Chemistry is the science of molecules and their  transformations.It is the science not so much of the one hundred elements but of the infinite variety of molecules that may be built from them.... 

                                      Ronald  Hoffmann 

'or'

Chemistry is the  branch of science that studies the composition, properties and interaction of matter. 

Importance of chemistry :-

Chemistry plays an important role in daily life. Chemistry plays a central role in science and is often intertwined with other branches of science like physics, biology, geology etc. Chemistry principals are important in deverse areas, such as :weather patterns, functioning of brain and operation of a computer. Chemistry industries manufacturing fertilizers, alkalis, acids, salts, dyes, polymers, drugs, soaps, detergents, metals, alloys and other inorganic and organic chemicals, including new materials ,contribute in a big way to the national economy. 

Many life saving drug  are:-

(a) Cisplatin and taxol, are effective in cancer therapy 

(b) Azt  (Azidothymidine)  used for helping AIDS victims, have been isolated from plant and animal sources or prepared by synthetic methods. 

Nature of Matter :-

Matter:- Anything which has mass and occupies space is called matter. Everything around us, for example -table, chair, fan, water all living beings etc. are composed by matter. 

Matter can exist in three physical states -Solidy, liquid and Gas 

Solid:-

Solid have definite space and volume. These particles are held very close to each other in an orderly fashion and there is not much freedom of movement. 

Liquid :-

Liquids have definite volume but not the definite

Shape. The particles are close to each other but they can move around. 

Gas :-

Gases have neither definite volume nor definite shape. The particles are afar apart as compared to the present in solid or liquid states and their movement is easy and fast 

 Macroscopic or bulk level :-

Matter can be classified as 'Mixture' or 'pure substances'.

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Many of the substance present around you are mixtures.for example - sugar solution. 

A mixture may be homogeneous or heterogeneous. 

Homogeneous mixture :-

The components completely mix with each other and it's composition is uniform throughout.example-sugar solution 

Heterogeneous mixture :-

The composition is not uniform throughout and sometimes the different components can be observed .for example - Grains  and pulses. 

Pure Substance:-

Pure substances have characteristics different from the mixtures.They have fixed composition, whereas mixtures may contain the components in any ratio and their composition is variable. For example - copper, silver etc pure substances can be further classified into element and components. 

Element:-

An element consists of only one type of particles. The particles may be atoms or molecules. 

Compound :-

When two or more atoms of different elements combine, the molecules of a compound is obtained. Example -water 

Properties of Matter and Their Measurement :-

These properties can be classified into two categories - 'physical properties ' and 'chemistry properties '.

Physical properties :-

Those properties which can be measured or observed without changing the identity or the composition of the substance. Example -Melting point, Density. 

Chemical properties :-

The measurement or observation of chemical properties require a chemical change to occur. 

The International system of units (SI) :-

The international system of units (in French Le systeme international d'unites -abbreviate as SI)  was established by the 11th (CGPM from conference Generale des poids at measures.).The CGPM is an inter governmental treaty organization created by a diplomatic treaty known as Meter Convention which is signed in Paris in 1875.

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Mass and weight :-

Mass of a substance is the amount of matter present in it  while is the force exerted by gravity on an object. 

Volume :-

Volume has the unit of 'length  cube '.so SI system, volume has units of 'meter cube '

Density :-

Density of a substance is it's amount of mass per unit volume 

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Temperature :-

There are three common scales to measure temperature -C(degree Celsius)  ,F (degree Fahrenheit) and  K (Kelvin). 

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Significant figures 

Laws of Chemical Combinations

Stoichiometry And Stoichiometry Calculations 

These three topic are available in my next blog. 

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