Consider the following neutral electron configurations in which 'n' has a constant value. Which configuration would belong to the element with the most negative electron affinity, E-ea?
a) ns^2
b) ns^2 np^2
c) ns^2 np^5
d) ns^2 np^6
would the answer be "d"??? (as in, it would be a noble gas with a p^6, and then have a more negative e- affinity???)
Unless I am out of date or misunderstood the question I thought that all electron affinities were shown as positive values. Those ending np^5 (e.g fluorine or chlorine) have the highest electron affinities.
If it is a noble gas, it has no affinity to attract an additional electron. I would examine the affintity of c) (as Fluorine, chlorine ).
The answer is c) ns^2 np^5
I know this because in addition to the explanations posted, above I just did this for my chemistry homework. I'm guessing you also have Mastering Chemistry?
To determine which electron configuration would belong to the element with the most negative electron affinity (E-ea), we need to consider the stability of the elements.
Electron affinity refers to the energy change when an atom gains an electron to form a negative ion. A more negative electron affinity indicates a greater energy release or stability upon gaining an electron.
In general, elements tend to follow the octet rule, which means they seek to achieve a stable electron configuration with eight valence electrons (except for the first shell, which requires two electrons).
Now let's analyze the given configurations:
a) ns^2: This configuration implies two valence electrons, which is less stable than a complete octet.
b) ns^2 np^2: This configuration also lacks stability since it has only four valence electrons.
c) ns^2 np^5: This configuration is close to a complete octet with seven valence electrons. However, it is still not as stable as having a complete octet.
d) ns^2 np^6: This configuration represents a complete octet, which is highly stable. It indicates that the element has a filled outer electron shell.
Therefore, the correct answer to the question is indeed option "d" - ns^2 np^6. This configuration signifies that the element has a noble gas electron configuration, which is the most stable arrangement. Elements with a noble gas configuration have a high negative electron affinity because they are already stable and resistant to gaining additional electrons.
The electron affinity is defined as the amount of energy ABSORBED when an electron is added to an isolated gaseous atom to form an ion with a 1- charge. The convention is to assign a positive value when energy is absorbed and a negative value when energy is released. For example, Be(g) + e + 241 kJ ==> Be^-(g) EA = +231 kJ/mol. (endothermic)
Cl(g) + e ==> Cl^-(g) + 348 kJ/mol EA = -348 kJ/mol (exothermic)
I think c is the answer.