Atomic and Nuclear PhysicsDOE-HDBK-1019/1-93ATOMIC NATURE OF MATTERr = (1.25 x 10-13cm) A1/3where: r = radius of the nucleus (cm)A = atomic mass number (dimensionless)The values of the nuclear radii for some light, intermediate, and heavy nuclides are shown inTable 2.TABLE 2Calculated Values for NuclearRadiiNuclideRadius of Nucleus11H1.25 x 10-13cm105B2.69 x 10-13cm5266Fe4.78 x 10-13cm17782Hf7.01 x 10-13cm23982U7.74 x 10-13cm25928Cf7.89 x 10-13cmFrom the table, it is clear that the radius of a typical atom (e.g. 2 x 10-8cm) is more than 25,000times larger than the radius of the largest nucleus.NuclearForcesIn the Bohr model of the atom, the nucleus consists of positively-charged protons and electrically-neutral neutrons. Since both protons and neutrons exist in the nucleus, they are both referred toas nucleons. One problem that the Bohr model of the atom presented was accounting for anattractive force to overcome the repulsive force between protons.Two forces present in the nucleus are (1) electrostatic forces between charged particles and (2)gravitational forces between any two objects that have mass. It is possible to calculate themagnitude of the gravitational force and electrostatic force based upon principles from classicalphysics.Rev. 0Page 7NP-01
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