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Atomic StructureDefinitions

Key Definitions

Part of Atomic Structure — GCSE Physics

This definitions covers Key Definitions within Atomic Structure for GCSE Physics. Revise Atomic Structure in Atomic Structure for GCSE Physics with 13 exam-style questions and 25 flashcards. This topic appears regularly enough that it should still be part of a steady revision cycle. It is section 7 of 12 in this topic. Make sure you can use the exact wording confidently, because definition marks are often lost through vague language.

Topic position

Section 7 of 12

Practice

13 questions

Recall

25 flashcards

📖 Key Definitions

Atomic number (Z): The number of protons in the nucleus of an atom. This defines the element.

Mass number (A): The total number of protons and neutrons (nucleons) in the nucleus.

Isotopes: Atoms of the same element with the same number of protons but different numbers of neutrons.

Nucleon: A particle found in the nucleus — either a proton or a neutron.

Ion: An atom that has lost or gained electrons, giving it an overall electric charge.

Keep building this topic

Read this section alongside the surrounding pages in Atomic Structure. That gives you the full topic sequence instead of a single isolated revision point.

How It Works: Why Some Nuclei Are UnstableCommon MisconceptionsMostly Empty SpaceInside the Atom

Practice Questions for Atomic Structure

What does the atomic number of an element tell you?

  • A. The number of neutrons in the nucleus
  • B. The total number of particles in the nucleus
  • C. The number of protons in the nucleus
  • D. The mass of one atom in grams
1 markfoundation

Describe the structure of an atom. Include the location and charge of the three main subatomic particles.

2 marksstandard

Quick Recall Flashcards

What are isotopes?
Isotopes are atoms of the same element (same number of protons) with different numbers of neutrons. This means they have the same atomic number but different mass numbers.
Why are atoms electrically neutral?
Atoms are electrically neutral because the number of protons (positive charges) equals the number of electrons (negative charges). The positive and negative charges cancel out.

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How It Works: Why Some Nuclei Are Unstable

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Common Misconceptions