Number of Elements w/ n <= 4: 60

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In summary, the conversation discusses the possible number of elements if elements with a principal quantum number greater than 4 were not allowed in nature. The options given are 60, 32, 4, and 64. The person attempting the problem initially gets 36 from the periodic table, but the correct answer is 60. The reason for this discrepancy is that the energy ordering of orbitals in real atoms is not solely based on the principal quantum number, leading to different electronic configurations.
  • #1
erisedk
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Homework Statement


If elements with principal quantum number n > 4 were not allowed in nature, the number of possible elements would be
(A) 60
(B) 32
(C) 4
(D) 64

Homework Equations

The Attempt at a Solution


I got 36 from the periodic table (2+8+8+18)
However, that isn't even an option. The answer is 60. Please help.
 
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  • #2
What are the rules that tell you how many electrons you can have for a given n?
 
  • #3
2n^2
 
  • #4
But looking from the periodic table, isn't my answer right?
 
  • #5
erisedk said:
But looking from the periodic table, isn't my answer right?
If you take only elements which have at most ##n=4## electrons, you indeed get a different number, but this is not what the question is about. What you get from the periodic table depends on the fact that the energy ordering of orbitals doesn't depend only on n, which makes it such that 5s electrons are lower in energy than 4d electrons. But the question says that n is at most 4, so when the 4p orbitals are filled, you will fill the 4d orbitals (and not the 5s as is the case for real atoms). You end up with different electronic configurations.
 
  • #6
Oh OK, so basically ignoring the energy order. Thank you!
 

What does "Number of Elements w/ n <= 4: 60" mean?

This means that there are a total of 60 elements that have a value less than or equal to 4.

Why is the number of elements limited to n <= 4?

This could be due to the specific parameters of a scientific experiment or study. The researcher may only be interested in elements with values within this range.

How was the number of elements determined?

The number of elements may have been determined through data analysis or experimental results. It could also be a predetermined value based on the research objectives.

What types of elements are included in this count?

This count may include any type of element, such as atoms, molecules, or particles. The specific types of elements may vary depending on the context of the research.

Are there any outliers or exceptions to this count?

This would depend on the specific data or experiment being analyzed. There may be outliers or exceptions that fall outside of the n <= 4 range, but they may not be included in this particular count.

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