The Nuclear Model Of The Atom
Overview
An atom is almost entirely empty space, with nearly all its mass packed into a tiny central nucleus. That surprising picture was forced on physicists by a famous experiment in which a few alpha particles bounced straight back off a thin gold foil, and it is the model we still use today.
In this lesson you will learn the structure of the atom, how ions form, the meaning of proton number and nucleon number, what an isotope is, and how the alpha-scattering experiment supports the nuclear model. You will also meet nuclear fission and fusion, the splitting and joining of nuclei.
Objectives
- Describe the structure of an atom in terms of a positively charged nucleus and negatively charged electrons in orbit around the nucleus
- Know how atoms may form positive ions by losing electrons or form negative ions by gaining electrons
- Describe the composition of the nucleus in terms of protons and neutrons
- State the relative charges of protons, neutrons and electrons as +1, 0 and –1 respectively
- Define the terms proton number (atomic number) Z and nucleon number (mass number) A and be able to calculate the number of neutrons in a nucleus
- Explain what is meant by an isotope and state that an element may have more than one isotope
- [Supplement] Describe how the scattering of alpha (α) particles by a sheet of thin metal supports the nuclear model of the atom, by providing evidence for: (a) a very small nucleus surrounded by mostly empty space (b) a nucleus containing most of the mass of the atom (c) a nucleus that is positively charged
- [Supplement] Describe the processes of nuclear fission and nuclear fusion as the splitting or joining of nuclei, to include the nuclide equation and qualitative description of mass and energy changes without values
- [Supplement] Know the relationship between the proton number and the relative charge on a nucleus
- [Supplement] Know the relationship between the nucleon number and the relative mass of a nucleus
Lesson Note
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Lesson Evaluation
Congratulations on completing the lesson on The Nuclear Model Of The Atom. Now that youve explored the key concepts and ideas, its time to put your knowledge to the test. This section offers a variety of practice questions designed to reinforce your understanding and help you gauge your grasp of the material.
You will encounter a mix of question types, including multiple-choice questions, short answer questions, and essay questions. Each question is thoughtfully crafted to assess different aspects of your knowledge and critical thinking skills.
Use this evaluation section as an opportunity to reinforce your understanding of the topic and to identify any areas where you may need additional study. Don't be discouraged by any challenges you encounter; instead, view them as opportunities for growth and improvement.
- The nucleus of an atom contains: A. protons and electrons B. protons and neutrons C. neutrons and electrons D. electrons only Answer: B
- An atom has A = 23 and Z = 11. Its number of neutrons is: A. 11 B. 12 C. 23 D. 34 Answer: B
- Isotopes of an element have the same number of: A. neutrons B. nucleons C. protons D. nothing Answer: C
- In alpha scattering, most alpha particles pass straight through the foil because: A. the atom is mostly empty space B. the nucleus is large C. atoms have no charge D. the foil is thick Answer: A
- An atom becomes a positive ion when it: A. gains electrons B. loses electrons C. gains protons D. loses neutrons Answer: B
Available on the Green Bridge App
Download the Green Bridge CBT app on your phone or computer to access full lesson notes, practice questions, and more.
Available on the Green Bridge App
Download the Green Bridge CBT app on your phone or computer to access full lesson notes, practice questions, and more.
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