8.2.3 Electron Affinity

Question 1

Electron Affinity

Answer 1

• 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.

Question 2

note

Answer 2

• 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 h ; 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.
• 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.

Question 3

Which of the following is the general periodic trend for increasing electron affinity?

Answer 3

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

Question 4

What is electron affinity?

Answer 4

The energy change that occurs when an atom gains an electron.

Question 5

Which of the following elements most strongly attracts an added electron to a neutral atom?

Answer 5

Chlorine

Question 6

How do electrons react to other electrons?

Answer 6

They are repelled by each other.

Question 7

How does the octet rule explain the common ion of oxygen?

Answer 7

Oxygen must gain 2 electrons to become stable

Question 8

Why does electron affinity generally increase as you go from left to right across the periodic table?

Answer 8

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.

Question 9

Which of the following represents chlorine in its ground state electron configuration?

Answer 9

1s22s22p63s23p5

Question 10

Which group has the highest electron affinity?

Answer 10

Halogens

Question 11

Why does chlorine have a higher electron affinity than fluorine?

Answer 11

Fluorine is a much more compact atom than chlorine

Question 12

Which of the following groups of elements is most likely to have a valence of 2–?

Answer 12

Chalcogens (the oxygen group)