BASIC CHEMICAL TERMS
A chemical substance is also known as pure substance, is form of matter
that have constant chemical composition and characteristic properties.
Chemical substances can be chemical elements, chemical compounds, irons or alloys.
Chemical Elements
Chemical elements are chemical substances which have only one type of atoms.
They cannot be broken down or transformed into different elements by any chemical reactions.
Eg. Fe, Al, Cu, C, Ti, Pt,....any periodic substance. There are total 118 chemical elements as of 2016.
Chemical Compound
Compounds are chemical substances that are formed from more than one elements, held together by chemical bonds. In other words they contains more than one type of atoms.
Combination of two or more chemical elements form single substance by chemical reaction and forms chemical compounds.
Eg. Fe3C, NaCl, H2O, NaOH, etc.
Mixtures
In chemistry, a mixture is a material made up of two or more different substances which are mixed but not chemically combined.
Mixture is a mechanical blend of two or more chemical substances.
Eg. Salt in water, suger in tea, etc.
Solid Solutions
When homogeneous mixture of two or more kinds of atoms occur in the solid state having definite crystalline structure, they are known as solid-solutions. ( Read More )
To clear your view on all of the terms given above let's consider some examples,
- Fe and C are two chemical elements
- α-ferrite is a solid solution of Fe and C.
- Fe3C ( Cementite ) is a chemical compound formed by Fe and C.
- Pearlite ( α-ferrite + Fe3C ) is a mixture of α-ferrite and cementite.
Because in pearlite, α-ferrite remains α-ferrite and Fe3C remains Fe3C. They are just mechanically combined.
System
In chemistry, a system is the part of the universe being studies. It is an isolated body of matter.
Component
In thermodynamics, a component is a chemically independent constituent of a system.
Eg. Steel is a two-component system, Iron-[Fe] (an element) and Cementite-[Fe3C] (an compound).