Stability of Atoms with half-filled orbitals

In summary: Hi, Thanks for your informative post! I have a few questions for you:1) How does the electron's binding energy to the nucleus factor into the stability of shells?2) Is it true that shells with more electrons are less stable?3) Can you explain Slater's rules in more detail?In summary, the electron's binding energy to the nucleus plays a role in the stability of shells. Half-filled and full shells are more stable because they have less instability. Slater's rules explain how this occurs.
  • #1
sarvesh0303
61
2
I have observed that when the outermost orbital is half filled (like Nitrogen 1s2 2s2 2p3), the atom has a higher stability (or a lower binding energy). Why is this so? I have heard it has to do with the fact that electron spin is maximized at that point but it still does not make sense to me.

Note: Please assume that I have very less knowledge of quantum mechanics. However, I am familiar with electron spin and quantum numbers, the Aufbau rule and the Pauli Exclusion Principle.
 
Chemistry news on Phys.org
  • #2
Hi,

I'm an Ametuer, but I believe the real reason for the stability of half filled shells is due to a decreased likelyhood of a reaction to occur that will fill or empty the 2p3 electron shell. Please take what I say with a grain of salt, because I'm more of a math and physics guy, but Chemistry is related to that in a lot of ways. Basically, half full outer shells for Nitrogen and other atoms appear to be more stable because they are in fact less stable. When you add one more electron, you raise the Coulomb energy of that orbital, so it has an uneven number of opposite spins, and that sort of throws it out of balance and the orbital tends to lose the electron because it requires less energy if the spins are even.

I'm sorry if I'm not very good at explaining this, but basically a reaction has to occur that donates a lot of electrons or takes a lot away in order to be favored over maintaining a balance because of the level of instability of shells that are slightly more than half full or slightly less than half full.

Hopefully someone will come along and either correct me or explain what I'm saying a little better.

Thanks, and good luck!

-Justin Hall
 
  • #3
sarvesh0303 said:
I have observed that when the outermost orbital is half filled (like Nitrogen 1s2 2s2 2p3), the atom has a higher stability (or a lower binding energy).

Please elaborate. Atom per se has no binding energy, unless it is a part of a molecule,
 
  • #4
I was asking about the electron's binding energy to the nucleus.
 
  • #5
When filling up a shell (or sub-shell) in an atom, the electrons in that shell, being all in orbitals of approximately the same size, are quite bad in shielding each other from the charge of the nucleus. Hence these electrons will be increasingly stronger attracted to the nucleus the more the shell is filled up due to the increase of effective nuclear charge.
This has been formalized in the Slater rules: http://en.wikipedia.org/wiki/Slater's_rules
However when you attemt to add a further electron to a half filled sub-shell, necessarily two electrons have to occupy the same orbital with increased Coulomb repulsion. So half filled and full shells are kind of optimal.
 

FAQ: Stability of Atoms with half-filled orbitals

1. What are half-filled orbitals and why are they important in the stability of atoms?

Half-filled orbitals refer to the electron configuration of an atom where the orbitals in the outermost energy level are only half-filled. This is important in the stability of atoms because it follows the Hund's rule, which states that electrons will occupy each orbital in a sublevel singly before pairing up. This arrangement leads to lower energy levels and thus, greater stability.

2. How do half-filled orbitals affect the reactivity of atoms?

Atoms with half-filled orbitals tend to be less reactive because they already have a stable electron configuration. This means they are less likely to gain or lose electrons in chemical reactions. As a result, these atoms are less likely to form compounds with other elements.

3. Can atoms with half-filled orbitals have magnetic properties?

Yes, atoms with half-filled orbitals can exhibit magnetic properties. This is because the electrons in the half-filled orbitals have unpaired spins, which create a magnetic field. This is why elements such as iron, cobalt, and nickel, which have half-filled orbitals in their outermost energy level, are magnetic.

4. How does the stability of atoms with half-filled orbitals change across the periodic table?

The stability of atoms with half-filled orbitals generally increases as you move across the periodic table from left to right. This is because the number of electrons in the outermost energy level increases, resulting in more half-filled orbitals. However, there are some exceptions to this trend, such as the noble gases, which have full outermost energy levels and are highly stable.

5. Can atoms with half-filled orbitals have multiple valence electrons?

Yes, atoms with half-filled orbitals can have multiple valence electrons. Valence electrons are the electrons in the outermost energy level, and they are the ones involved in chemical bonding. For example, carbon has four valence electrons, two of which are in a half-filled orbital, making it stable and allowing it to form multiple bonds with other elements.

Similar threads

Back
Top