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Radioactivity

Forming ions, and how the atomic model changed

  • 2 things to know
  • Paper 1

Overview

Ions and ionisation, how atoms become positive ions, the plum pudding model, alpha particle scattering in Rutherford's laboratory, the nuclear and Bohr models, why models of the atom changed, and peer review and communicating scientific results.

What you need to know

Answer each one before you reveal it.

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Key term

What is an ion?

Key term

A neutral atom loses two outer electrons. What is the charge on the ion formed?

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    What is an ion?

    Model answer

    An ion is an atom that has gained or lost electrons and so carries an overall charge.

  2. 2

    Explain how an atom becomes a positive ion.

    Model answer

    It loses one or more outer electrons, so its protons then outnumber its electrons.

  3. 3

    A neutral atom loses two outer electrons. What is the charge on the ion formed?

    Model answer

    The ion has a charge of +2.

  4. 4

    What is meant by ionisation?

    Model answer

    Ionisation is the removal of electrons from atoms, leaving charged particles behind.

  5. 5

    Why is it the outer electrons that are lost when an atom becomes a positive ion?

    Model answer

    Outer electrons are furthest from the nucleus and so are the least strongly attracted to it.

  6. 6

    How does radiation from a radioactive source create positive ions in the air around it?

    Model answer

    It transfers enough energy to knock outer electrons off the air atoms.

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