Element , Compound and Mixture
Division of matter:
The various forms of matter are divided into main two classes : Elements and Compounds & a third class mixture can also be added in the list.
Whatever matter of found in nature or around us it is either element , compound or mixture.
An element is substance which can neither be split up into two or more similar substances nor it can be built up from any other simpler matter by any known chemical process.
We can say a substance is in it’s elemental form of matter if it consists of atoms having identical chemical properties.
For example : Pure iron is entirely composed of iron atoms and all of it’s atoms have same identical properties. And we cannot divide the pure iron into any other substances , so Pure iron is in it’s elemental form.
Examples of elements are : Hydrogen , Silver , Nitrogen , Copper , Silicon etc.
Currently there are 105 different elements known among which 92 elements are believed to exist in nature and rest have been synthesised in laevorotatory by artificial means.
Among the elements found in nature only about one fourth occur in nature in the free state ; the others are found in combination.
Elements have been further divided into metals , non-metals and metalloids.
Metals are generally , malleable , ductile and are good conductor of heat and electricity. Some examples of metal are ; iron , gold , aluminium , lead , sodium etc.
The non-metals are not good conductor of heat and electricity and they do not have other metallic properties like hardness , ductility etc. Come examples of non-metals are ; Carbon , Sulphur , Iodine , Bromine etc.
Elements which shows the both properties of metals and non-metals are called metalloids , some examples of metalloids are ; arsenic , antimony etc.
A compound is a substance composed of the atoms of two or more elements combined in a definite proportion by weight.
Elements when combined together have different properties than it’s constituent elements or elements in the free or un-combined state.
And if two or more atoms are combined to form a molecule then the substance made up of those molecules are called compounds. For example : Sugar , water.
Water is a compound because each molecule of water contains atoms of hydrogen and oxygen in the ratio 1:8 by weight.
Whereas there are only 105 known elements , the number of chemical compounds obtained by the combination of these elements are thousands of thousands or almost infinite. And each of these compounds possesses definite chemical and physical properties by which they can be distinguished from all other compounds.
A chemical compound is produced as a result of chemical change and generally in this process energy in the form of hear , light etc. is either absorbed or evolved. Components of a compound cannot be separated by simple physical means , to separate the components of a compound the compound must go though the chemical change.
A mechanical mixture is a substance composed of two or more compounds or elements in any proportion by weight such that each of which retains it’s identity and specific properties.
If two or more compounds or elements are mixed up mechanically in any proportion by weight then the new substance is called mixture. In a mixture each of it’s constituent matter retains it’s properties and doesn’t go through chemical change. Fo example: Cement , milk , flour etc.