ionization energy

Examples of ionization energy in the following topics:

• Ionization Energy

  • Large atoms or molecules have low ionization energy, while small molecules tend to have higher ionization energies.
  • The greater the ionization energy, the more difficult it is to remove an electron.
  • The ionization energy may be an indicator of the reactivity of an element.
  • This graph shows the first ionization energy of the elements in electron volts.
  • This video explains the periodic trends in ionization energy....periodicity.

• Electron Affinity

  • Mulliken used a list of electron affinities to develop an electronegativity scale for atoms by finding the average of the electron affinity and ionization potential.
  • For any reaction that releases energy, the change in energy (ΔE) has a negative value, and the reaction is called an exothermic process.
  • The trends noted here are very similar to those in ionization energy and change for similar (though opposing) reasons.
  • Periodic Properties: Part 4, Ionic Charges, Ionization Energy, Electron Affinity - YouTube
  • We conclude our discussion of periodic properties by wrapping up the prediction of ionic charges of the transition metals, ionization energies, and electron affinity.

• General Trends in Chemical Properties

  • Elements in the same group show patterns in atomic radius, ionization energy, and electronegativity.
  • From top to bottom, each successive element has a lower ionization energy because it is easier to remove an electron since the atoms are less tightly bound.
  • Elements in the same period show trends in atomic radius, ionization energy, electron affinity, and electronegativity.
  • The decrease in atomic radius also causes ionization energy to increase from left to right across a period: the more tightly bound an element is, the more energy is required to remove an electron.
  • Electronegativity increases in the same manner as ionization energy because of the pull exerted on the electrons by the nucleus.

• Properties of Sulfur

  • The first and the second ionization energies of sulfur are 999.6 and 2252 kJ/mol, respectively.
  • The fourth and sixth ionization energies are 4556 and 8495.8 kJ/mol.

• Electron Configuration of Cations and Anions

  • Atoms can be ionized by bombardment with radiation, but the more purely chemical process of ionization is the transfer of electrons between atoms or molecules.
  • Atoms will gain or lose electrons depending on which action takes the least energy.
  • The ionization of sodium can be chemically illustrated as follows:
  • The energy required to do so may be recorded in a successive ionization energy diagram.
  • Note that the maximum ionization energy for each row diminishes as one progresses from row 1 to row 7 in a given column, due to the increasing distance of the outer electron shell from the nucleus as inner shells are added.

• Anchimeric Assistance

  • The following energy profiles for these reactions illustrate the sequence of events.
  • Both reactions begin by an initial rate-determining ionization step, the transition state of which is colored pink.
  • The activation energy for this step is larger for neopentyl chloride because it leads to a discrete 1º-carbocation.
  • The essential difference is that the ionization transition state for neopentyl chloride suffers all the disadvantages associated with the generation of a 1º-carbocation; whereas, the transition state for ionization of triphenylethyl chloride is lowered in energy by its phenonium-like character.
  • Anchimeric assistance not only manifests itself in enhancement of ionization, but also influences the stereochemical outcome of reactions.

• Addition by Electrophilic Reagents

  • This is seen in the ionization potentials of ethylene and acetylene.
  • As defined by the preceding equations, an ionization potential is the minimum energy required to remove an electron from a molecule of a compound.
  • Since pi-electrons are less tightly held than sigma-electrons, we expect the ionization potentials of ethylene and acetylene to be lower than that of ethane, as is the case.
  • Application of the Hammond postulate indicates that the activation energy for the generation of a vinyl cation intermediate would be higher than that for a lower energy intermediate.
  • This is illustrated for alkenes versus alkynes by the following energy diagrams.

• The Photoelectric Effect

  • However, if the energy of the light is such that the electron is excited above energy levels associated with the atom, the electron can actually break free from the atom leading to ionization of the atom.
  • In the photoemission process, if an electron within some material absorbs the energy of one photon and acquires more energy than the work function of the material (the electron binding energy), it is ejected.
  • If excess photon energy is absorbed, some of the energy liberates the electron from the atom and the rest contributes to the electron's kinetic energy as a free particle.
  • The maximum kinetic energy of an ejected electron is given by
  • The maximum kinetic energy of an ejected electron is then

• Measuring Radiation Exposure

  • Radiation dosimetry is the measurement and calculation of the absorbed dose from exposure to indirect and direct ionizing radiation.
  • Radiation dosimetry is the measurement and calculation of the absorbed dose in matter and tissue resulting from exposure to indirect and direct ionizing radiation.
  • Radiation dose refers to the amount of energy deposited in matter and/or biological effects of radiation.
  • Exposure to a radioactive source will give a dose that is dependent on the activity, time of exposure, energy of the radiation emitted, distance from the source, and shielding.
  • There are several ways of measuring doses from ionizing radiation, including personal dosimeters and ionization chambers.

• Mass Spectrometry to Measure Mass

  • First, the sample is ionized.
  • There are a wide variety of techniques for ionizing and detecting compounds.
  • The ion source is the part of the mass spectrometer that ionizes the compound.
  • This high-energy beam strips electrons from the sample molecules, leaving behind a positively charged radical species.
  • The components of the sample are ionized by one of a variety of methods, such as the ionizing filament.