Ionization Energy and Electron Affinity
In physics and chemistry, ionization energy (American English spelling) or ionisation energy When the next ionization energy involves removing an electron from the same electron shell, the .. Electron affinity – a closely related concept describing the energy released by adding an electron to a neutral atom or molecule. Source_ Difference Between Electron Affinity and Ionization Energy | Definition, Description, Similarities and Differences Main Difference – Electron Affinity vs. Certain properties—notably atomic radius, ionization energy, electron affinity and metallic character—can be qualitatively understood by the.
In other words, ionization is accompanied by vibrational excitation. The intensity of such transitions are explained by the Franck—Condon principlewhich predicts that the most probable and intense transition corresponds to the vibrational excited state of the positive ion that has the same geometry as the neutral molecule.
This transition is referred to as the "vertical" ionization energy since it is represented by a completely vertical line on a potential energy diagram see Figure.
Periodic Trends: Atomic Size, Ionization Energy, and Metallic Character - Chemistry LibreTexts
For a diatomic molecule, the geometry is defined by the length of a single bond. The removal of an electron from a bonding molecular orbital weakens the bond and increases the bond length. In Figure 1, the lower potential energy curve is for the neutral molecule and the upper surface is for the positive ion.
Both curves plot the potential energy as a function of bond length. The horizontal lines correspond to vibrational levels with their associated vibrational wave functions. Since the ion has a weaker bond, it will have a longer bond length.
This effect is represented by shifting the minimum of the potential energy curve to the right of the neutral species. The adiabatic ionization is the diagonal transition to the vibrational ground state of the ion.
Therefore, S should have the larger magnitude of EA.
Oxygen - Electron Affinity - Electronegativity - Ionization Energy of Oxygen - Nuclear Power
Electron Affinities Predict which atom will have the highest magnitude of Electron Affinity: Br Metallic Character The metallic character is used to define the chemical properties that metallic elements present. Generally, metals tend to lose electrons to form cations. Nonmetals tend to gain electrons to form anions. They also have a high oxidation potential therefore they are easily oxidized and are strong reducing agents.
Metals also form basic oxides; the more basic the oxide, the higher the metallic character. Courtesy of Jessica Thornton UCD As you move across the table from left to right, the metallic character decreases, because the elements easily accept electrons to fill their valance shells. Therefore, these elements take on the nonmetallic character of forming anions.
As you move up the table, the metallic character decreases, due to the greater pull that the nucleus has on the outer electrons. This greater pull makes it harder for the atoms to lose electrons and form cations. Uses in knowing the Periodic Properties of Elements Predicting greater or smaller atomic size and radial distribution in neutral atoms and ions Measuring and comparing ionization energies Comparing electron affinities and electronegativities Predicting redox potential Comparing metallic character with other elements; its ability to form cations Predicting what reaction may or may not occur due to the trends Determining greater cell potential sum of oxidation and reduction potential between reactions Completing chemical reactions according to trends Summary Certain properties—notably atomic radius, ionization energies, and electron affinities - can be qualitatively understood by the positions of the elements on the periodic table.
Atomic size is the distance from the nucleus to the valence shell where the valence electrons are located. Atomic radius is a more definite and measurable way of defining atomic size. The first ionization energies for the main group elements are given in the two figures below.
Two trends are apparent from these data. In general, the first ionization energy increases as we go from left to right across a row of the periodic table. The first ionization energy decreases as we go down a column of the periodic table.
The first trend isn't surprising. We might expect the first ionization energy to become larger as we go across a row of the periodic table because the force of attraction between the nucleus and an electron becomes larger as the number of protons in the nucleus of the atom becomes larger.
The second trend results from the fact that the principal quantum number of the orbital holding the outermost electron becomes larger as we go down a column of the periodic table.
Although the number of protons in the nucleus also becomes larger, the electrons in smaller shells and subshells tend to screen the outermost electron from some of the force of attraction of the nucleus.