Electron screening of nuclear charge

In summary, the reason alkali metals have the largest radii but smallest ionization energies is because screening is least effective for a lone electron outside a closed shell.
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Homework Statement


I have a multichoice past exam that does not come with answers. Please help with the following:


The reason why alkali metals have the largest radii but smallest ionisation energies is best described by the fact:

a) screening is least effective for a lone electron outside a closed shell
b) screening is most effective for a lone electron outside a closed shell
c) screening is least effective for a lone electron in an s-orbital outside a closed shell
d) screening is most effective for a lone electron in an s-orbital outside a closed shell



Homework Equations



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The Attempt at a Solution



I chose B. D seems plausible too, but I think sometimes the s-orbital isn't always the lowest energy orbital for a given principal quantum number.


Thanks
 
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  • #2
for reaching out for help on this question! The answer is actually A) screening is least effective for a lone electron outside a closed shell. This is because alkali metals have only one valence electron, which is located in the outermost s-orbital. This electron is not well screened or shielded from the positive charge of the nucleus by the other electrons in the atom. As a result, it is easier to remove this electron and form a positive ion, resulting in a smaller ionization energy. Additionally, the large atomic radius of alkali metals is due to the low effective nuclear charge experienced by the valence electron, which is not well screened. I hope this helps clarify the concept for you!
 

FAQ: Electron screening of nuclear charge

1. What is electron screening of nuclear charge?

Electron screening of nuclear charge is a phenomenon in which the negatively charged electrons surrounding the nucleus of an atom partially shield the positive charge of the nucleus, reducing its effective charge.

2. How does electron screening affect nuclear reactions?

Electron screening can affect nuclear reactions by lowering the Coulomb barrier, which is the energy barrier that must be overcome for two nuclei to fuse together. This can increase the rate of nuclear reactions and potentially change the outcome of the reaction.

3. Can electron screening be observed in experiments?

Yes, electron screening has been observed in experiments using techniques such as scattering experiments and beta decay measurements. These experiments have provided evidence for the existence of electron screening and have helped to refine our understanding of the phenomenon.

4. What factors affect the strength of electron screening?

The strength of electron screening depends on the number of electrons surrounding the nucleus, the distance between the electrons and the nucleus, and the energy of the electrons. As these factors change, the amount of screening also changes, impacting the overall strength of the phenomenon.

5. How does electron screening impact the stability of atoms?

Electron screening plays a crucial role in the stability of atoms by reducing the overall positive charge of the nucleus and increasing the binding energy of the electrons. This helps to keep the electrons in orbit and maintain the overall stability of the atom.

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