Class 9 Science NCERT Solutions -Ch-2 Is Matter around us Pure?
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In this article, we will discuss ‘Is matter around us pure?’ from 9th Class Science. We all know that all the matter around us is not pure. There are two types of Matter – pure substances and mixtures. We will discuss both in detail.
Pure Substances: Elements and compounds
A pure substance is one which is made up of only one kind of particles. A pure substance is one which is made up of only one kind of atoms or molecules. All the elements and compounds are pure substances because they contain only one kind of elements.
E.g.: -Iodine, mercury, silicon, iron, copper, bromine.
All compounds such as water, sodium hydroxide, nitric acid are pure substances.
A pure substance is homogeneous throughout its mass. It cannot be separated into other kinds by any physical process.
Impure substances: Mixtures
A mixture is one which contains two or more different kinds of particles. The Mixture contains two or more pure substances and mixed together. All the mixtures are impure substances.
E.g.: – Salt solution, milk, sea water, biogas, tea, coffee.
A mixture can be homogeneous and heterogeneous. It can be separated into other kinds of matter by a physical process. It does not have a fixed composition or fixed melting or boiling point.
Most of the matter around us exists as mixtures of two or more pure substances.
From the above discussion, we can conclude all the matter can be divided into three classes: Elements, compounds, and mixtures.
Before proceeding further, we should understand three important terms malleability, ductility, and brittleness:-
Malleability– The property which allows the metals to be hammered or beaten into a thin sheet.
Ductility- The property which allows the metals to be drawn into thin wires.
Brittleness-The property due to which nonmetals break into pieces on hammering is called brittleness
An element is a substance which cannot be split into two or more simpler substances by the usual chemical methods of applying heat, light, or electric energy.
An element cannot be split up into two or more simpler substances because it is made of only one kind of atoms. An element is a substance which is made of only one kind of atoms.
There are 115 elements known at present, out of which 92 elements occur in nature, while the remaining 23 elements are prepared artificially. Every element in this world is made up of one or more of these elements.
E.g.: – Hydrogen, helium, oxygen, nitrogen, carbon, sulphur.
Elements can be solids, liquids or gases. Majority of elements are solids. 11 elements are gases. And only two elements mercury and bromine are liquids at room temperature.
Few elements combine together in different ways to make an extremely large number of materials
On the basis of their properties, all the elements can be divided into three groups:
We will now discuss these in details one by one in further articles for 9th Class. Keep watching the website for more.
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