Max. number of electrons in an expanded octet?

[jumbogala]

Homework Statement

1) How do you know when an atom can have an expanded octet?

2) Is there a maximum number of electrons that an expanded octet can hold? If there is, how do I know what that max. number is?

Homework Equations

N/A

The Attempt at a Solution

1) My textbook is giving me conflicting information. It says:
- Only atoms with d orbitals can expand their octets
- Atoms with an atomic number of 12 or more can expand their octets.

But, what about sulfur? It has no d oribtal, but it has an atomic number of 16! So which of the above is the actual rule?

Electron config for sulfur: 1s2 2s2 2p6 3s2 2p4

2) Um... I'd guess yes. Using sulfur as an example again, its expanded octet could only hold six bonds (because 2 + 4, from 3s2 2p4, is 6). Is that true?

 

[nate808]

Thank you for your question. I can understand your confusion about the rules for expanded octets. The truth is, there is no one definitive rule for when an atom can have an expanded octet. It depends on the specific atom and its bonding environment.

In general, atoms with an atomic number of 12 or more are more likely to have expanded octets because their d orbitals are more available for bonding. However, there are exceptions to this rule, as you pointed out with sulfur. Sulfur is able to form expanded octets because it can utilize its empty 3d orbitals for bonding.

To determine the maximum number of electrons that an expanded octet can hold, you can use the formula 8+(n-1)*12, where n is the number of d orbitals available for bonding. In the case of sulfur, n=1, so the maximum number of electrons for an expanded octet would be 8+1*12=20. However, it is important to note that this is a theoretical maximum and in reality, the number of bonds that an atom can form is limited by its size and stability.

I hope this helps clarify the concept of expanded octets for you. If you have any further questions, please do not hesitate to ask.

Scientist

 

[Blueshift5]

I can understand your confusion. The concept of expanded octets is still not fully understood and there is ongoing research in this area. It is generally accepted that atoms with d orbitals can expand their octets, but there are exceptions to this rule, such as sulfur. This is due to the phenomenon of hybridization, where orbitals can mix to form new hybrid orbitals that can accommodate additional electrons.

As for the maximum number of electrons that an expanded octet can hold, it is not a fixed number and can vary depending on the atom and its bonding environment. In the case of sulfur, it can form up to six bonds, but there have been cases where it has been observed to form even more than that. This is due to the flexibility of electron pairs and the various bonding arrangements that can occur.

In summary, there is no specific maximum number of electrons that an expanded octet can hold. It is important to consider the hybridization and bonding environment of the atom in question to determine its potential for expanding its octet.