Hetrick, Dynamics of Nuclear Reactors, American Nuclear Society, 1993, ISBN: 3-2. Neuhold, Introductory Nuclear Reactor Dynamics, American Nuclear Society, 1985, ISBN: 9-4. Bezella, Introductory Nuclear Reactor Statics, American Nuclear Society, Revised edition (1989), 1989, ISBN: 3-2. Department of Energy, Nuclear Physics and Reactor Theory.В DOE Fundamentals Handbook,В Volume 1 and 2.В JanuaryВ 1993. Robert Reed Burn, Introduction to Nuclear Reactor Operation, 1988.Physics of Nuclear Kinetics.В Addison-Wesley Pub. Nuclear and Particle Physics.В Clarendon Press 1 edition, 1991, ISBN:В 978-0198520467 Nuclear Reactor Engineering: Reactor Systems Engineering,В Springer 4th edition, 1994, ISBN:В 978-0412985317 Not all elements form stable negative ions in which case the electron affinity is zero or even positive. So the more negative the electron affinity the more favourable the electron addition process is. Stacey, Nuclear Reactor Physics, John Wiley & Sons, 2001, ISBN: 0- 471-39127-1. The electron affinity is the potential energy change of the atom when an electron is added to a neutral gaseous atom to form a negative ion. Baratta, Introduction to Nuclear Engineering, 3d ed., Prentice-Hall, 2001, ISBN: 8-1. Lamarsh, Introduction to Nuclear Reactor Theory, 2nd ed., Addison-Wesley, Reading,В MA (1983). The electron affinities of the noble gases have not been conclusively measured, so they may or may not have slightly negative values. Chlorine most strongly attracts extra electrons. Nonmetals like to gain electrons to form anions to have a fully stable electron shell. Nonmetals: Generally, nonmetals have more positive electron affinity than metals.Mercury most weakly attracts an extra electron. The electron affinity of metals is lower than that of nonmetals. Metals: Metals like to lose valence electrons to form cations to have a fully stable shell.This affinity is known as the second electron affinity and these energies are positive. However, more energy is required to add an electron to a negative ion which overwhelms any the release of energy from the electron attachment process. By convention, the negative sign shows a release of energy. This affinity is known as the first electron affinity and these energies are negative. When an electron is added to a neutral atom, energy is released. To use electron affinities properly, it is essential to keep track of sign. Electron affinities are more difficult to measure than ionization energies.ДЄ fluorine atom in the gas phase, for example, gives off energy when it gains an electron to form a fluoride ion.ДЇ + e вЂ“ в†’ F вЂ“ вЂ“ в€†H = Affinity = 328 kJ/mol Note that, ionization energies measure the tendency of a neutral atom to resist the loss of electrons. In other words, it can be expressed as the neutral atomвЂ™s likelihood of gaining an electron. The change in energy (in kJ/mole) of a neutral atom or molecule (in the gaseous phase) when an electron is added to the atom to form a negative ion. The protons attached to that atom will be deshielded.ДЄs the electronegativity of the substituent increases, so does the extent of deshielding, and so does the chemical shift.In chemistry and atomic physics, the electron affinity of an atom or molecule is defined as: The less electronegative atom will have a decreased electron density.

The greater the electronegativity difference #О”EN# between the two atoms, the more the electron density will be pulled toward the more electronegative atom. Hydrogen is assigned an arbitrary value of 2.20 'Pauling units'. This gives a dimensionless quantity on a relative 'Pauling scale' that runs from around 0.7 to 3.98. It must be calculated from other properties such as bond energies, ionization energies, and electron affinities of the bonded atoms. Electron affinity value measured by unit eV per atom or kJ mol-1. For example,Д®lectronegativity, #П‡#, is the tendency of an atom to attract toward itself the electron density in a shared bond.Д®lectronegativity cannot be directly measured. The above electron affinity equation is an exothermic reaction with the negative sign according to the usual thermodynamics convention in chemistry but the measurement of affinities is always the positive value. It is usually reported as the energy per mole of atoms. It can be expressed only in arbitrary dimensionless units with respect to a reference atom.Д®lectron affinity, EA, measures the energy released when an electron adds to a gaseous atom. It is an energy term and is measured in units of joules per mole.Д®lectronegativity is a property of an atom in a molecule. Electron affinity is a property of an isolated atom in the gaseous state.

Electron affinity definition