Table of Contents
Table of Contents
- Mixtures, Compounds, and Elements
- Periodic Classification
- Summary
- Did You Know?
- What’s Next?
In this segment of the chapter ‘Periodic Classification of Elements’, let us get introduced to
periodic classification.
What are mixtures, compounds, and elements?
- Substances which do not contain everything in a fixed proportion are called Mixtures. Substances can be added or removed from a mixture.
- Substances that contain everything in a fixed proportion are called Compounds. When the proportion of substances is changed, it affects the compound.
For example, if one hydrogen is removed from ?2?,that is water, the composition changes and water as a compound does not exist.
Thus, a fixed proportion is compulsory in compounds.
- The purest forms of any known substance are called Elements. They are composed of only the same type of atoms. There are neither proportions nor random mixing of substances. Compounds and mixtures are made up of elements.
What is the Periodic classification of elements?
- The total number of elements known to mankind is 118.
- To study these elements, they should be organised appropriately.
- Arranging the various elements is the first step towards understanding their properties. This arrangement helps in organising or classifying the elements.
- Classification of elements is categorising the various elements into groups, based on similarities and differences in their properties.
- The classification system helps in grouping the various elements into categories which are called Periods. Hence, the system is also called Periodic Classification of Elements.
