nuclei

• Nucleus

  The central core of the atom where the entire positive charge and most of the mass of the atom is concentrated
• Nucleus


  • Can be charged
  • Constituents are nucleons (protons and neutrons)
• Atomic number (Z)


  The number of protons in the nucleus of an atom
• Mass number (A)


  The total number of protons and neutrons in the nucleus of an atom
• No two elements that are different can have the same atomic number
• Even two different elements can have the same mass number
• More the number of nucleons in the nucleus

  The greater the mass number
• More the number of nucleons in the nucleus

  The greater the volume of the nucleus
• Density of the nucleus is independent of the mass number
• Density of the nucleus

  Mass/Volume
• Calculating the radius of a nucleus

  1. R = R0 * A^(1/3)

  2. Where R0 = 1.2 fm
• The volume of the nucleus is proportional to the mass number (A)
• The density of the nucleus is constant at around 2.3 x 10^17 kg/m^3
• Isotopes

  Atoms of the same element having different mass numbers (different number of neutrons)
• Isobars


  Different elements having the same mass number
• Isotopes have the same chemical properties as they have the same number of protons
• Isobars have different chemical properties as they have different numbers of protons
• Binding energy of the nucleus

  The energy required to separate the nucleons in the nucleus into individual particles
• Greater the binding energy of the nucleus

  More stable the nucleus
• Greater the mass defect of the nucleus


  Greater the binding energy of the nucleus
• The mass defect of the nucleus is converted into binding energy during the formation of the nucleus
• E=mc^2 is used to calculate the binding energy of the nucleus from the mass defect
• The binding energy per nucleon is a better way of comparing the stability of different nuclei