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Nucleus - GCSE Chemistry Definition

Reviewed by: Richard Boole

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The nucleus is the central part of an atom, and it contains most of the atom’s mass. It is made up of two types of particles:

  • Protons, which have a positive charge

  • Neutrons, which have no charge

The number of protons in the nucleus is called the atomic number, and it determines which element the atom is. Electrons, which are negatively charged, move around the nucleus in shells. Even though protons repel each other because they are positively charged, the nucleus is held together by a strong nuclear force.

In GCSE Chemistry, understanding the nucleus is important for explaining atomic structure, isotopes, and how elements are arranged in the Periodic Table.

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Richard Boole

Reviewer: Richard Boole

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Richard has taught Chemistry for over 15 years as well as working as a science tutor, examiner, content creator and author. He wasn’t the greatest at exams and only discovered how to revise in his final year at university. That knowledge made him want to help students learn how to revise, challenge them to think about what they actually know and hopefully succeed; so here he is, happily, at SME.

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