7.1+THE+ATOM

IB Physics > 7 Atomic and Nuclear Physics [|IB Physics Atomic and Nuclear Physics objectives in Word] - link to Google doc [|IB ATOMIC AND NUCLEAR PHYSICS DEFINITIONS AND CONCEPTS] - link to Google doc THE ATOM helpful diagrams =THE ATOM= INTERESTIN ATOMIC STRUCTURE 7.1.1 Describe a model of the atom that features a small nucleus surrounded by electrons. Students should be able to describe a simple model involving electrons kept in orbit around the nucleus as a result of the electrostatic attraction between the electrons and the nucleus.  
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 * 7.1 ATOM || 7.2 RADIOACTIVE DECAY || 7.3 NUCLEAR REACTIONS ||

NUCLEAR MODEL OF THE ATOM: Mass and positive charge concentrated in tiny nucleus with negative electrons around it.

7.1.2 Outline the evidence that supports a nuclear model of the atom. A qualitative description of the Geiger-Marsden experiment and an interpretation of the results are all that is required.

7.1.3 Outline one limitation of the simple model of the nuclear atom. LIMITATION OF NUCLEAR MODEL: A classical atom would decay quickly since the electrons would spiral into the nucleus.

7.1.4 Outline evidence for the existence of atomic energy levels. ATOMIC ENERGY LEVELS: Bohr and Planck proposed distinct energy levels for electrons (quanta). [|EMISSION AND ABSORPTION SPECTRA] - applet from European Space Agency Students should be familiar with emission and absorption spectra, but the details of atomic models are not required. Students should understand that light is not a continuous wave but is emitted as “packets” or “photons” of energy, each of energy //hf//.

NUCLEAR STRUCTURE
7.1.5 Explain the terms nuclide, isotope and nucleon.

NUCLIDE: A combination of protons and neutrons that form a nucleus.

ISOTOPE: Nuclei with the same number of protons but different numbers of neutrons.

NUCLEON: The particles in the nucleus (proton or neutron).

7.1.6 Define //nucleon number A//, //proton number Z// and //neutron number N//.

NUCLEON NUMBER, A: The number of nucleons in the nucleus.

PROTON NUMBER, Z: The number of protons in the nucleus.

NEUTRON NUMBER, N: duh! N=A-Z

7.1.7 Describe the interactions in a nucleus. Students need only know about the Coulomb interaction between protons and the strong, short‑range nuclear interaction between nucleons.

NUCLEAR STRONG FORCE: The force that holds the particles of a nucleus together. It is strong enough to overcome electrostatic repulsion of protons and very short range so that nuclei don’t attract each other.