Electron Affinity (8.2.3) Flashcards
• Electron affinity (EA) is the energy released when an electron is added to a neutral atom.
• Electron affinity (EA) is the energy released when an electron is added to a neutral atom.
• Electron affinity generally increases in magnitude toward the top and the right on the periodic table.
• Electron affinity generally increases in magnitude toward the top and the right on the periodic table.
Electron affinity (EA) is the energy released when an electron is added to a neutral atom.
When an electron is added to a neutral atom the result is
a monovalent anion. When the electron is introduced, a
photon is released with the energy hν; X + e– = X– + EA.
Electron affinity (EA) is the energy released when an electron is added to a neutral atom.
When an electron is added to a neutral atom the result is
a monovalent anion. When the electron is introduced, a
photon is released with the energy hν; X + e– = X– + EA.
Electron affinity generally increases in magnitude toward
the top and the right on the periodic table.
Going down the first group of the periodic table the
vacancies in the valence shells are further and further
from the nucleus and the electron affinity is not as large.
Going from left to right the effective nuclear charge
increases. As the effective nuclear charge increases so
does electron affinity.
Electron affinity generally increases in magnitude toward
the top and the right on the periodic table.
Going down the first group of the periodic table the
vacancies in the valence shells are further and further
from the nucleus and the electron affinity is not as large.
Going from left to right the effective nuclear charge
increases. As the effective nuclear charge increases so
does electron affinity.
In the alkaline earths, EA is close to or greater than 0, so
little energy is released when the electron is added.
Because they have the maximum effective nuclear
charge, the halogens have the highest EA of any
elements.
Oxygen and fluorine are small atoms with high nuclear
charges that pull all the electrons very close together.
Chlorine and sulfur are larger atoms, so there is less
repulsion among the electrons. Because the extra
electron resides in a larger orbital in chlorine and sulfur,
those elements have a higher EA than oxygen and
fluorine.
In the alkaline earths, EA is close to or greater than 0, so
little energy is released when the electron is added.
Because they have the maximum effective nuclear
charge, the halogens have the highest EA of any
elements.
Oxygen and fluorine are small atoms with high nuclear
charges that pull all the electrons very close together.
Chlorine and sulfur are larger atoms, so there is less
repulsion among the electrons. Because the extra
electron resides in a larger orbital in chlorine and sulfur,
those elements have a higher EA than oxygen and
fluorine.
Which of the following is the general periodic trend for increasing electron affinity?
(A)
In general, the electron affinity increases as you move up a group and to the right across the periodic table. There are exceptions, but this is the general trend.
Which of the following groups of elements is most likely to have a valence of 2–?
Chalcogens (the oxygen group) (C.)
The chalcogens readily accept two electrons. So, they have a valence of 2−.
How does the octet rule explain the common ion of oxygen?
Oxygen must gain 2 electrons to become stable. (B)
Oxygen has six electrons in its outer shell. To fill its outer shell, it must gain two electrons rather than lose two electrons to become stable. The ion of oxygen has 8 electrons in its outer shell and therefore, has a 2− charge.
Why does chlorine have a higher electron affinity than fluorine?
Fluorine is a much more compact atom than chlorine. (D)
Fluorine is a much more compact atom than chlorine. Chlorine has a greater electron affinity because it has more electrons and this serves to shield to the outer electrons in chlorine more than in fluorine.
Why does electron affinity generally increase as you go from left to right across the periodic table?
The elements on the right side of periodic table usually have a larger number of protons and a smaller atomic radius than elements on the left side of the periodic table. (A)
The number of protons increases moving from left to right across the periodic table, and the atomic radii decrease. The ability to add an electron to a neutral atom depends on the number of protons causing the attraction compared to the volume of the electron cloud.
What is electron affinity?
The energy change that occurs when an atom gains an electron. (D)
Electron affinity is defined as the energy change when an electron is added to a neutral atom in a gaseous sample; X + e− → X − + EA; when EA
Which group has the highest electron affinity?
Halogens (C)
The halogens have the highest electron affinity. The halogens need to accept one electron to completely fill their outer orbital.
Which of the following elements most strongly attracts an added electron to a neutral atom?
Chlorine (A)
Chlorine has the most negative value for electron affinity. Thus, chlorine most strongly attracts an added electron.
Which of the following represents chlorine in its ground state electron configuration?
1s^2 2s^2 2p^6 3s^2 3p^5 (D)
This is the ground state electron configuration for chlorine.
How do electrons react to other electrons?
They are repelled by each other. (B)
Electrons have negative charges. Like charges repel each other.
