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Questions and Answers
Which statement accurately describes the relationship between electron affinity (EA) and the energy change when an electron is accepted by an atom?
Which statement accurately describes the relationship between electron affinity (EA) and the energy change when an electron is accepted by an atom?
- EA is the inverse of the energy change.
- EA is unrelated to the energy change.
- EA is the negative of the energy change. (correct)
- EA is equal to the energy change.
For an element with a high electron affinity, what is generally true regarding its tendency to accept an electron?
For an element with a high electron affinity, what is generally true regarding its tendency to accept an electron?
- It has a low tendency to accept an electron.
- It has a moderate tendency to accept an electron.
- The tendency is unrelated to electron affinity.
- It has a high tendency to accept an electron. (correct)
If a reaction is exothermic, what is the sign of the change in enthalpy ($\Delta H$) and the nature of the electron affinity?
If a reaction is exothermic, what is the sign of the change in enthalpy ($\Delta H$) and the nature of the electron affinity?
- $\Delta H$ is positive, and electron affinity is positive.
- $\Delta H$ is negative, and electron affinity is negative.
- $\Delta H$ is negative, and electron affinity is positive. (correct)
- $\Delta H$ is positive, and electron affinity is negative.
How does the effective nuclear charge generally correlate with electron affinity across the periodic table?
How does the effective nuclear charge generally correlate with electron affinity across the periodic table?
What is the general trend in electron affinity as you move from left to right across a period in the periodic table?
What is the general trend in electron affinity as you move from left to right across a period in the periodic table?
Which group of elements typically has very low or negative electron affinity values?
Which group of elements typically has very low or negative electron affinity values?
Why do noble gases exhibit a low tendency to accept an electron?
Why do noble gases exhibit a low tendency to accept an electron?
What is characteristic of the electron affinity of Group 17 elements (halogens)?
What is characteristic of the electron affinity of Group 17 elements (halogens)?
Why does fluorine (F) not follow the general trend of increasing electron affinity going up Group 17?
Why does fluorine (F) not follow the general trend of increasing electron affinity going up Group 17?
What best describes the electron affinity of metals compared to nonmetals?
What best describes the electron affinity of metals compared to nonmetals?
What is the electron affinity of fluorine?
What is the electron affinity of fluorine?
Consider the elements oxygen, sulfur, and selenium. Predict the order of increasing electron affinity values for these elements.
Consider the elements oxygen, sulfur, and selenium. Predict the order of increasing electron affinity values for these elements.
Elements often exhibit exceptions to general electron affinity trends, particularly across a period. Which of the following correctly orders elements from Group 1A to 2A according to their electron affinity?
Elements often exhibit exceptions to general electron affinity trends, particularly across a period. Which of the following correctly orders elements from Group 1A to 2A according to their electron affinity?
Based on their electronic configurations and the principles of electron affinity, which of the following sequences correctly orders elements according to increasing electron affinity across a period?
Based on their electronic configurations and the principles of electron affinity, which of the following sequences correctly orders elements according to increasing electron affinity across a period?
Given the halogens Chlorine(Cl), Bromine(Br), and Iodine(I), arrange them in order of increasing electron affinity.
Given the halogens Chlorine(Cl), Bromine(Br), and Iodine(I), arrange them in order of increasing electron affinity.
Specify which of the following elements you would expect to have the greatest electron affinity: Helium (He), Potassium (K), Cobalt (Co), Sulfur (S) or Chlorine (Cl)
Specify which of the following elements you would expect to have the greatest electron affinity: Helium (He), Potassium (K), Cobalt (Co), Sulfur (S) or Chlorine (Cl)
Flashcards
Electron Affinity (EA)
Electron Affinity (EA)
The negative of the energy change when an electron is added to a gaseous atom to form an anion.
Energy change (ΔH)
Energy change (ΔH)
The energy released or absorbed when an electron is added to a gaseous atom.
EA Trend Across a Period
EA Trend Across a Period
Going across a row (left to right) of the periodic table, electron affinity generally increases.
EA Trend Down a Group
EA Trend Down a Group
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Highest Electron Affinity
Highest Electron Affinity
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Noble Gases (Group 18)
Noble Gases (Group 18)
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Fluorine's Electron Affinity
Fluorine's Electron Affinity
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Electron Affinity Exceptions
Electron Affinity Exceptions
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Positive Energy Change
Positive Energy Change
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Example with Cl
Example with Cl
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Study Notes
Electron Affinity
- Electron affinity refers to the energy change when an electron is added to an element; mostly nonmetals undergo this process.
- Electron affinity is the negative of the energy change when an atom in its gaseous state accepts an electron to become an anion.
- Considering fluorine, the process is: F(g) + e- -> F-(g)
- DH = -331 kJ/mol, making EA = +331 kJ/mol
- A positive electron affinity indicates an exothermic reaction, while a negative electron affinity indicates an endothermic reaction.
- The more positive the electron affinity, the greater an atom's affinity for accepting an electron.
- A higher EA means more energy is released, making it easier to add electrons.
- Metals generally have a lower electron affinity than nonmetals.
- Noble gasses typically have very low or negative EA values due to their stable electronic configuration.
- As you move across a period from left to right, electron affinity generally becomes more positive.
- As you move down a group, electron affinity generally decreases.
Trends and Exceptions
- There is a general correlation between electron affinity and effective nuclear charge; both increase from left to right on the periodic table.
- As one goes down a group, electron affinities decrease.
- Fluorine breaks this pattern because it is a small atom which leads to crowding and repulsion, making the attraction of incoming electrons less.
- In column 17, EA presents itself as: I < Br < F < Cl
- Adding one electron to group 2A creates a new subshell, while in 1A it will complete an already existing subshell.
- Adding an electron to group 5A creates the first paired electron, causing greater electrostatic repulsion.
- The electron affinity periodic trend generally follows as: 8A < 2A < 1A < 3A < 5A < 4A < 6A< 7A
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