Basic Definition and classification of Matter | class 9th | chemistry | Fundamental of chemistry.

Matter is simply defined as anything that has mass and occupies space. Our bodies as well as all the things around us are examples of matter. In chemistry, we study all types of matters that can exist in any of three physical states: solid, liquid or gas. A piece of matter in pure form is termed as a substance. Every substance has a fixed composition and specific properties or characteristics. Whereas, impure matter is called a mixture; which can be homogeneous or heterogeneous in its composition. We know that every substance has physical as well as chemical properties. The properties those are associated with the physical state of the substance are called physical properties like colour, smell, taste, hardness, shape of crystal, solubility, melting or boiling points, etc. For example, when ice is heated, it melts to form water. When water is further heated, it boils to give steam. In this entire process only the physical states of water change whereas its chemical composition remains the same. The chemical properties depend upon the composition of the substance. When a substance undergoes a chemical change, its composition changes and a new substances are formed. For example, decomposition of water is a chemical change as it produces hydrogen and oxygen gases. All materials are either a substance or a mixture.
Modern definition of element is that it is a substance made up of same type of atoms, having same atomic number and cannot be decomposed into simple substances by ordinary chemical means. It means that each element is made up of unique type of atoms that have very specific properties.
Compound is a substance made up of two or more elements chemically combined together in a fixed ratio by mass. As a result of this combination, elements lose their own properties and produce new substances (compounds) that have entirely different properties.
When two or more elements or compounds mix up physically without any fixed ratio, they form a mixture. On mixing up, the component substances retain their own chemical identities and properties. The mixture can be separated into parent components by physical methods such as distillation, filtration, evaporation, crystallisation or magnetization. Mixtures that have uniform composition throughout are called homogeneous mixtures e.g. air, gasoline, ice cream. Whereas, heterogeneous mixtures are those in which composition is not uniform throughout e.g. soil, rock and wood.
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[mahabatkhan]

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[waleedkhattak]

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[Study]

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[Study]

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