Notes : Complete chapter 5 - Inside the atom, class 8, General science?

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Inside the Atom - Class 8 General Science

Atoms are the smallest units of matter that can exist independently and are made up of subatomic particles like protons, neutrons, and electrons. In this chapter, we will explore the structure of an atom, the properties of its subatomic particles, and the different models of the atom proposed by scientists over time.

The Structure of an Atom

An atom consists of a central nucleus made up of positively charged protons and neutral neutrons.

Electrons orbit the nucleus in shells or energy levels.

The number of protons in the nucleus determines the atomic number of an element.

The total number of protons and neutrons in the nucleus is called the atomic mass.

Properties of Subatomic Particles

Protons have a positive charge and a mass of 1 atomic mass unit (amu).

Neutrons have no charge and a mass of 1 amu.

Electrons have a negative charge and a negligible mass.

The number of protons and electrons in an atom is equal, making the atom electrically neutral.

Models of the Atom

The Thomson model proposed that the atom was a positively charged sphere with negatively charged electrons embedded in it.

The Rutherford model suggested that the atom had a small, dense, positively charged nucleus with electrons orbiting it.

The Bohr model improved upon the Rutherford model by proposing that electrons move in orbits of fixed energy levels around the nucleus.

The modern quantum mechanical model describes electrons as existing in probability clouds or orbitals around the nucleus.

Conclusion

The study of the atom has led to a better understanding of matter, energy, and the universe. It has also paved the way for advancements in fields like medicine, technology, and energy. As scientists continue to explore the mysteries of the atom, we can expect to see even more breakthroughs in the future.

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It is not present t in NCERT textbook for grade 8.I think you are talking about some other book...

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What is the difference in the atomic models of thomson and rutherord

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