Octet Rules

[Cassidy Kohlenberger 3D]

What is the difference between an element that does not have to satisfy the octet rule, and an element that can have an extended octet? I think, I might be wrong, that all elements group 3 and below can have an extended octet?

[Lauren Bui 1E]

If an atom does not satisfy the octet rule, it means there are less than 8 electrons (i.e. the first 4 elements of the periodic table). An expanded octet refers to when there are more than 8 electrons; these are also known as exceptions to the octet rule.

[Rebekah Alfred 1J]

In the review session today, it was mentioned that the elements (with a d-orbital) in Period 3 and later can have an expanded octet.

[Rebekah Alfred 1J]

If an atom does not satisfy the octet rule, it means there are less than 8 electrons (i.e. the first 4 elements of the periodic table). An expanded octet refers to when there are more than 8 electrons; these are also known as exceptions to the octet rule.

Examples of elements that typically have less than an octet/do not satisfy the octet rule (as Lauren mentioned) are Hydrogen, Helium, Lithium, and Beryllium. Examples of elements that can have an expanded octet are Phosphorus, Sulfur, and Chlorine.

[Katie Kyan 2K]

Elements that can have expanded octets are the elements in row 3 and beyond. If we look at the principal quantum number for period 3 elements (n=3), we see that the angular momentum number can be all values up to n-1. This means that the angular momentum number can take on the values of 0,1, or 2. Since l=2 corresponds to the d-orbital and the elements in period 3 don't have any electrons in this orbital, these elements and those beyond can have an expanded octet. The elements that do not have a full octet are H, He, Li, and Be. Elements in the column of Boron can have either an expanded octet or a not filled one.