Exploring Hund's Rule with Different n Shells

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In summary, Hund's rule states that the lowest-energy state of an atom is determined by the combined values of the spin and angular momentum of its electrons, with the greatest S and L having the lowest energy. This applies to all possible combinations of angular momentum and spin for a given number of electrons.
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salsero
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Does Hund's rule also apply when combining the angular momenta of electrons from shells with DIFFERENT quantum number n?
 
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I'm not sure of what you mean. Hund's rule does not have to do with "combining angular momenta", but rather with filling subshells.
 
  • #3
Suppose there are n electrons with angular momentum quantum numbers L1, L2, L3, ..., Ln. The total angular momentum L of the atom can be any number between the minimum and the maximum of all non-negative combinations +/- L1 +/- L2 +/- L3 ... +/- Ln (in steps of 1). Same about combinations of the spin (the spin quantum numbers of the single electrons are always 1/2) to the total spin S of the atom.

Hund's rule says that the lowest-energy state among all the possible states is the state which has the greatest S and the greatest L (for that S).
 
  • #4
Originally posted by salsero
Suppose there are n electrons with angular momentum quantum numbers L1, L2, L3, ..., Ln. The total angular momentum L of the atom can be any number between the minimum and the maximum of all non-negative combinations +/- L1 +/- L2 +/- L3 ... +/- Ln (in steps of 1). Same about combinations of the spin (the spin quantum numbers of the single electrons are always 1/2) to the total spin S of the atom.

Hund's rule says that the lowest-energy state among all the possible states is the state which has the greatest S and the greatest L (for that S).

If it's true in two cases, it's true in all (in this case)

Best wishes
 
  • #5
What?
 

1. What is Hund's rule and why is it important in chemistry?

Hund's rule is a rule that explains how electrons are distributed in an atom's orbitals. It states that electrons will fill empty orbitals before pairing up in the same orbital. This rule is important in chemistry because it helps explain the properties of elements and their reactivity.

2. How does the number of n shells affect the application of Hund's rule?

The number of n shells, or energy levels, in an atom directly affects the application of Hund's rule. As the number of n shells increases, the number of orbitals and sublevels also increases, making it more likely for electrons to fill empty orbitals before pairing up.

3. How can we explore Hund's rule with different n shells?

One way to explore Hund's rule with different n shells is by using electron configuration diagrams or orbital filling diagrams. These diagrams can help visualize the distribution of electrons in different energy levels and sublevels according to Hund's rule.

4. Are there any exceptions to Hund's rule?

Yes, there are a few exceptions to Hund's rule. For example, elements in the transition metal group may have a slightly different electron configuration due to the stability of half-filled or fully-filled sublevels. Additionally, atoms with half-filled sublevels may have a slightly lower energy state than those with partially filled sublevels.

5. How does understanding Hund's rule help us predict the properties of elements?

Understanding Hund's rule allows us to predict the electron configuration of elements, which in turn helps us understand their properties. For example, elements with a partially filled outer energy level tend to be more reactive because they are more likely to gain or lose electrons to achieve a full outer energy level.

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