Bihar Board - Class 11 - Chemistry - Chapter 2: Structure of Atom Handwritten Notes

The "Structure of Atom" chapter explores the fundamental building blocks of matter—atoms. It introduces the concepts of atomic structure, helping students understand the arrangement of protons, neutrons, and electrons within an atom. This chapter forms the foundation for understanding chemical reactions, bonding, and the behavior of elements.

Key Points:

1. Atom and Its Components:

   • An atom is the smallest unit of matter, made up of three subatomic particles: protons, neutrons, and electrons.
   • Protons are positively charged, neutrons are neutral, and electrons are negatively charged.

2. Nucleus of the Atom:

   • The nucleus is the dense, positively charged center of the atom, consisting of protons and neutrons.
   • The electrons revolve around the nucleus in specific energy levels or shells.

3. Bohr's Model of the Atom:

   • Bohr's model explains that electrons orbit the nucleus in fixed energy levels or orbits.
   • The energy of electrons increases as they move away from the nucleus.

4. Atomic Number and Mass Number:

   • Atomic number is the number of protons in the nucleus and defines the element.
   • Mass number is the total number of protons and neutrons in an atom.

5. Isotopes and Isobars:

   • Isotopes are atoms of the same element with different numbers of neutrons (e.g., Carbon-12 and Carbon-14).
   • Isobars are atoms of different elements with the same mass number.

6. Electron Distribution:

   • Electrons are arranged in shells around the nucleus. The maximum number of electrons in a shell is given by the formula $$2n22n^2, where $$nn is the shell number.

7. Valence Electrons:

   • Electrons in the outermost shell of an atom are called valence electrons and play a key role in chemical bonding.

8. Important Atomic Models:

   • Thomson's Model: Proposed the "plum pudding" model where electrons were embedded in a positively charged sphere.
   • Rutherford's Model: Suggested that the atom has a small, dense, positively charged nucleus with electrons orbiting around it.

Conclusion:

The "Structure of Atom" chapter lays the groundwork for understanding the atomic nature of matter. By understanding the components of an atom—protons, neutrons, and electrons—students are able to comprehend the basic principles of chemistry. This chapter is crucial for further study in chemical bonding, reactions, and the periodic table. Mastering atomic structure enables students to explore the behavior of elements and their interactions in the world of chemistry.

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