Matter And Its States


States Of Matter - Concepts
Class - RRB Technician Grade III Subjects
 
 
Concept Explanation
 

Matter And Its States

Introduction: Chemistry is the science of the composition of matter, its properties and characteristics, and the changes it undergoes. Chemistry deals with the properties that distinguish one  another.

The burning of coal, gas, and wood; the cooking of meat and other foods; the rusting of the kitchen knife and the tarnishing of silver - all these things, which we take for granted, involve chemical changes. Life processes such as growth, digestion and breathing are also examples of chemical change.

States Of matter: The physical classification separates matter into three categories - solids, liquids and gases - known as the three states (phases) of matter. Plasma, highly ionised gas, is sometimes considered a fourth state of matter.

Elements, Compounds and Mixtures: An element may be defined as the simplest form of matter that cannot be decomposed by ordinary chemical means into simpler substances, nor can it be formed by the combination of other substances, or an element is a substance made up of atoms with the same atomic number.

The common examples of elements are hydrogen, oxygen, nitrogen, iron, gold, copper, mercury, carbon, etc. There are 106 elements known at present. Out of these, about 92 have so far been found to occur naturally and the remaining 14 have been prepared in the laboratories.

Oxygen and silicon are the most common elements and they are the major constituents of sand, soil and rocks. Oxygen also occurs as free element in the atmosphere and in combination with hydrogen in water. The most common elements found in 'our body are oxygen, carbon, hydrogen nitrogen, calcium, phosphorus, etc.

A number of elements, found in only very slight traces or not at all in nature, have been synthesised. Those elements are technetium, promethium, astatine, francium and all the elements with atomic number above 92.

Compound: It may be noted that a chemical compound always contains the same elements in definite (fixed) proportion by weight. For example, water always contains hydrogen and oxygen in the ratio of 1:8 by weight. Thus, we may define a compound as a substance made up of two or more elements chemically combined in a fixed proportion by weight, A compound has properties all its own.

Mixtures: Most of the objects that we see around us are not pure substances (like elements and compounds) bat these are mixtures because they contain two or more substances in different proportions. A material obtained by mixing two or more substances (elements or compounds) in any proportion is known as mixture.

Mixtures are of two types: homogeneous mixtures and heterogeneous mixtures.

 
 
 


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