effective nuclear charge

Examples of effective nuclear charge in the following topics:

• The Shielding Effect and Effective Nuclear Charge

  • The shielding effect, approximated by the effective nuclear charge, is due to inner electrons shielding valence electrons from the nucleus.
  • As an approximation, we can estimate the effective nuclear charge on each electron.
  • The effective nuclear charge on an electron is given by the following equation:
  • What is the effective nuclear charge for each?
  • Diagram of the concept of effective nuclear charge based on electron shielding.

• Nuclear Fission

  • Most fissions are binary fissions that produce two charged fragments.
  • Occasionally, about 2 to 4 times per 1000 events, three positively charged fragments are produced, which indicates a ternary fission.
  • The strong nuclear force is the force between two or more nucleons.
  • The electromagnetic force causes the repulsion between like-charged protons.
  • These two forces produce opposite effects in the nucleus.

• Nuclear Fusion

  • The protons are positively charged and repel each other, but they nonetheless stick together, demonstrating the existence of another force referred to as nuclear attraction.
  • This force, called the strong nuclear force, overcomes electric repulsion in a very close range.
  • The effect of nuclear force is not observed outside the nucleus, hence the force has a strong dependence on distance; it a short-range force.
  • At large distances, two nuclei repel one another because of the repulsive electrostatic force between their positively charged protons.
  • The electrostatic force, on the other hand, is dependent upon the inverse-square of the distance between two like-charged particles, so a proton added to a nucleus will feel an electrostatic repulsion from all the other protons in the nucleus.

• Charge Distribution in Molecules

  • Similarly, nitromethane has a positive-charged nitrogen and a negative-charged oxygen, the total molecular charge again being zero.
  • Finally, azide anion has two negative-charged nitrogens and one positive-charged nitrogen, the total charge being minus one.
  • Because of their differing nuclear charges, and as a result of shielding by inner electron shells, the different atoms of the periodic table have different affinities for nearby electrons.
  • Electronegativity differences may be transmitted through connecting covalent bonds by an inductive effect.
  • Excellent physical evidence for the inductive effect is found in the influence of electronegative atoms on the nmr chemical shifts of nearby hydrogen atoms.

• Fusion Reactors

  • Fusion power is the power generated by nuclear fusion processes.
  • Fusion between the nuclei is opposed by the repulsive positive electrical charge common to all nuclei because they contain protons.
  • The easiest way to do this is to heat the atoms, which has the side effect of stripping their electrons and leaving them as bare nuclei.
  • The temperatures required to provide the nuclei with enough energy to overcome their repulsion is a function of the total charge.
  • Therefore, hydrogen, which has the smallest nuclear charge, fuses at the lowest temperature, and is often used as fuel.

• Nuclear Stability

  • An isotope's nuclear stability depends on the balance of electric and nuclear forces between its protons and neutrons and their arrangement.
  • In nuclear physics, stability of an atom's nucleus depends on the number of protons and neutrons it contains.
  • The protons, which are both positively charged, repel one another through electrostatic force.
  • This force is offset by the nuclear force, which attracts protons and neutrons.
  • This is because, for any constant number of protons, the difference between nuclear force and electrostatic repulsion of protons increases with increasing neutron count.

• Isotopes in Medicine

  • Nuclear medicine is a medical specialty that involves the application of radioactive substances to diagnose or treat disease.
  • In nuclear medicine procedures, radionuclides are combined with other elements to form chemical compounds.
  • In nuclear medical imaging, radiopharmaceuticals are taken internally, either intravenously or orally.
  • The radiopharmaceuticals used in nuclear medicine therapy emit ionizing radiation that travels only a short distance.
  • This thereby minimizes unwanted side effects and damage to noninvolved organs or nearby structures.

• Nuclear Binding Energy and Mass Defect

  • This energy—available as nuclear energy—can be used to produce nuclear power or build nuclear weapons.
  • Nuclear binding energy is also used to determine whether fission or fusion will be a favorable process.
  • As such, there is a peak at iron-56 on the nuclear binding energy curve.
  • The rationale for this peak in binding energy is the interplay between the coulombic repulsion of the protons in the nucleus, because like charges repel each other, and the strong nuclear force, or strong force.
  • Calculate the mass defect and nuclear binding energy of an atom

• Atomic Size

  • no effect at all as the two opposing tendencies of electron repulsion and nuclear attraction balance each other out.
  • Experiments have shown that the first case is what happens: the increase in nuclear charge overcomes the repulsion between the additional electrons in the valence level.

• Balancing Nuclear Equations

  • To balance a nuclear equation, the mass number and atomic numbers of all particles on either side of the arrow must be equal.
  • The transformations of particles must follow certain conservation laws, such as conservation of charge and baryon number, which is the total atomic mass number.
  • To balance the equation above for mass, charge, and mass number, the second nucleus on the right side must have atomic number 2 and mass number 4; it is therefore also helium-4.
  • Instead of using the full equations in the style above, in many situations a compact notation is used to describe nuclear reactions.
  • Describes how to write the nuclear equations for alpha and beta decay.