NCERT Solutions for Class 11 Chemistry Chapter 1- Some Basic Concepts of Chemistry

This chapter introduces students to the classification of matter based on the nature of their substances which include pure substances and mixtures and the properties of these matters and their measurement. This chapter recalls the International System of Units (SI). It also deals with other topics like Mass, Wright, Density, and Temperature of substances and teaches students Scientific Notations, Significant Figures and their calculations through Addition and Subtraction and Multiplication and Division.

Students also learn Analysis of Dimensions and Law of Chemical Combinations, Dalton's Atomic Theory, calculation of Mass of Atoms and Molecules, and methods to balance a chemical equation.

• International System of Units (SI)

This topic recalls the definition, name, symbols and prefixes of SI units. Some names and their symbols in SI units are meters (m), kilogram (kg), second (s), Ampere (A).

• Scientific Notations

This topic teaches students how to write large numbers in simplified scientific notation format. Example 0.00016 can be written as 1.6 × 10-4.

• Significant Figures

Significant figures are meaningful digits which are known with certainty plus one which is estimated or uncertain. A few rules have also been listed out to determine the number of significant figures.

• Dimension Analysis

The method used to convert units from one system to the other is called Dimension Analysis. It is also called a factor label method or unit factor method.

• Law of Chemical Combinations

Five different laws are explained for students to understand the combination of elements to form compounds. They are Law of Conservation of Mass, Law of Definite Proportions, Law of Multiple Proportions, Gay Lussac's Law of Gaseous Volumes, and Avogadro's Law.

• Dalton's Atomic Theory

This theory helps students understand all matter in terms of atoms. The first part of the theory states that all matter is made of invisible atoms, and the second part of the theory says all atoms of a given element are identical in mass and properties.

• Atoms and Molecular Masses

In this topic, students learn to calculate the atomic mass and molecular mass which is the sum of atomic masses of the elements present in a molecule.

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