Multiple Choice
Which of the following elements has the highest (most negative) electron affinity?
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10. Periodic Properties of the Elements
Periodic Trend: Electron Affinity
Multiple Choice
Which of the following elements has the greatest electron affinity (largest positive value)?
A
Na
B
Cl
C
O
D
Ar
Verified step by step guidance1
Understand that electron affinity is the energy change that occurs when an atom gains an electron. A more negative electron affinity value means the atom releases more energy and has a stronger tendency to gain an electron.
Recall the general trend of electron affinity in the periodic table: it increases (becomes more negative) across a period from left to right and decreases down a group.
Identify the positions of the elements in the periodic table: Na (Group 1, Period 3), O (Group 16, Period 2), Cl (Group 17, Period 3), and Ar (Group 18, Period 3).
Compare the elements based on their group and period: halogens (Group 17) like Cl typically have the highest electron affinities because they are one electron short of a full octet, making them very eager to gain an electron.
Conclude that Cl has the greatest electron affinity among the given elements because it is a halogen with a nearly full valence shell, leading to a large release of energy when it gains an electron.
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