The Nuclear Model Of The Atom
Aperçu
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.
Objectifs
- 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
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Évaluation de la leçon
Félicitations, vous avez terminé la leçon sur The Nuclear Model Of The Atom. Maintenant que vous avez exploré le concepts et idées clés, il est temps de mettre vos connaissances à lépreuve. Cette section propose une variété de pratiques des questions conçues pour renforcer votre compréhension et vous aider à évaluer votre compréhension de la matière.
Vous rencontrerez un mélange de types de questions, y compris des questions à choix multiple, des questions à réponse courte et des questions de rédaction. Chaque question est soigneusement conçue pour évaluer différents aspects de vos connaissances et de vos compétences en pensée critique.
Utilisez cette section d'évaluation comme une occasion de renforcer votre compréhension du sujet et d'identifier les domaines où vous pourriez avoir besoin d'étudier davantage. Ne soyez pas découragé par les défis que vous rencontrez ; considérez-les plutôt comme des opportunités de croissance et d'amélioration.
- 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
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Livres recommandés
Pour aller plus loin, ressources libres
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Section de manuel
Substructure of the Nucleus
What is inside the nucleus? Why are some nuclei stable while others decay? (See Figure 31.12 .) Why are there different types of decay ( α α size 12{α} {} , β β size 12{β} {} and γ γ size 12{γ} {} )? Why are nuclear decay energies so large? Pursuing natural questions like these has led to far more f
"College Physics: Substructure of the Nucleus" by OpenStax, OpenStax, Rice University, licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Source: https://openstax.org/books/college-physics/pages/31-3-substructure-of-the-nucleus. Access for free at https://openstax.org/books/college-physics/pages/1-introduction
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Section de manuel
Discovery of the Parts of the Atom: Electrons and Nuclei
Just as atoms are a substructure of matter, electrons and nuclei are substructures of the atom. The experiments that were used to discover electrons and nuclei reveal some of the basic properties of atoms and can be readily understood using ideas such as electrostatic and magnetic force, already cov
"College Physics: Discovery of the Parts of the Atom: Electrons and Nuclei" by OpenStax, OpenStax, Rice University, licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Source: https://openstax.org/books/college-physics/pages/30-2-discovery-of-the-parts-of-the-atom-electrons-and-nuclei. Access for free at https://openstax.org/books/college-physics/pages/1-introduction
Publiées par d'autres organisations sous licence libre, créditées comme elles le demandent. Les liens ouvrent leurs sites.
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