For which of these elements would the electron affinity process shown be least favorable?
1. H + e− ! H−
2. Li + e− ! Li−
3. F + e− ! F−
4. O + e− ! O−
5. N + e− ! N−
My best guess would have been Li, but apparently the answer is N, which has almost zero electron affinity.
See
http://www.webelements.com/periodicity/electron_affinity/
for value for those elements. (Drag the cursor to the element.)
The electron affinity process refers to the gain of an electron by an atom in the gas phase. It represents the energy change when an electron is added to a neutral atom to form a negative ion.
To determine which of the given elements would have the least favorable electron affinity process, we need to consider the trends in electron affinity across the periodic table.
Generally, electron affinity tends to increase from left to right across a period and decrease from top to bottom within a group. This means that elements on the right-hand side of the periodic table tend to have higher electron affinity values.
Let's analyze each option:
1. H + e− → H−: Hydrogen is on the leftmost side of the periodic table and has a low electron affinity.
2. Li + e− → Li−: Lithium is in period 2 and is in the second group. It has relatively low electron affinity.
3. F + e− → F−: Fluorine is on the right side of the periodic table and has the highest electron affinity among the given options. This means the electron affinity process is most favorable for fluorine.
4. O + e− → O−: Oxygen is to the right of nitrogen and has a higher electron affinity compared to hydrogen and lithium but lower than fluorine.
5. N + e− → N−: Nitrogen is in the same group as phosphorus, and its electron affinity is relatively low compared to fluorine.
Therefore, based on the trends in electron affinity, the option with the least favorable electron affinity process is option 2: Li + e− → Li− (lithium).