Maharashtra Board Class 11 Chemistry Chapter 1 Some Basic Concepts of Chemistry PDF Download

Some Basic Concepts of Chemistry

Introduction

Chemistry is the study of matter, its physical and chemical properties and the physical and chemical changes it undergoes under different conditions.

Chemistry is a central science. Its knowledge is required in the studies of physics, biological sciences, applied sciences, and earth and space sciences. The scope of chemistry is in every aspect of life, for example, the air we breathe, the food we eat, the fluids we drink, our clothing, transportation and fuel supplies, and so on.

Though it is an ancient science, due to development and advancement in science and technology, chemistry has developed as modern science. Technological development in sophisticated instruments expanded our knowledge of chemistry which, now, has been used in applied sciences such as medicine, dentistry, engineering, agriculture and in daily home use products.

Teacher's Note

Chemistry helps us understand everything around us - from the water we drink to the medicines we take. For example, when milk turns into yogurt, that is chemistry happening in our kitchen!

Exam Trick

Remember: Chemistry is everywhere in your life. Just like cooking food involves chemical changes, your body also uses chemistry to digest food and grow.

Points to Remember

Chemistry is the study of matter and its changes.
Chemistry is used in medicine, agriculture, and many other fields.
Chemistry helps us understand the world around us.
Ancient science but very modern in use today.

Nature of Chemistry

Chemistry is traditionally classified further into five branches: organic, inorganic, physical, bio and analytical. Organic chemistry is the study of the properties and reactions of compounds of carbon. Inorganic chemistry is the study of all substances which are not organic. Physical chemistry is the study of principles underlying chemistry. It deals with the studies of properties of matter. It is study of atoms, molecules, and fundamental concepts related to electrons, energies and dynamics therein. It provides basic framework for all the other branches of chemistry.

Matter

You have learnt earlier that matter occupies space and has mass. Matter can be further classified into pure substances and mixtures on the basis of chemical composition.

Pure Substances Versus Mixtures

Pure substances have a definite chemical composition. They always have the same properties regardless of their origin. Mixtures have no definite chemical composition and hence no definite properties.

Examples of pure substances: Pure metal, distilled water, etc.

Examples of mixtures: Paint (mixture of oils, pigment, additive), concrete (a mixture of sand, cement, water)

Pure substances are further divided into elements and compounds. Elements are pure substances which can not be broken down into simpler substances by ordinary chemical changes. Elements are further classified as metals, nonmetals and metalloids.

Teacher's Note

A pure substance like pure gold always looks and behaves the same. But a mixture like tea is different - it depends on how much sugar and milk you add to it.

Exam Trick

Remember: Pure substance = always same. Mixture = can be different. For example, Ganga water is a mixture, but pure H2O is always the same.

Points to Remember

Matter is divided into pure substances and mixtures.
Pure substances have fixed composition and properties.
Mixtures do not have fixed composition.
Elements cannot be broken down by normal chemical changes.
Compounds are made of two or more elements combined.

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