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To know if an atom has an expanded octet, you don’t have to memorize it. All you need to know is that an element that is in the 3rd period and beyond can have an expanded octet. So say you’ve done the Lewis structure for XeF4, it has 36 valence electrons and since fluorine can’t have double bonds, because it can’t have an expanded octet, you would put two lone pairs around Xe, in which Xe is allowed to have an expanded octet since its not in the 1st or 2nd row.
alexagreco1A wrote:We know that only the elements that are in Group 3 or below can form an expanded octet, as they have unfilled d-orbitals, which Groups 1 and 2 do not have.
This is absolutely correct. keep in mind that these elements dont necessarily always have an expanded octet and are completely happy with 8 electrons however this empty d-orbital (3d and on) allows them to accept more electrons if needed.
Elements in the 1st and 2nd period do not have access to the the d orbital which prevents them from having an expanded octet, therefore elements that are in the 3rd period and below have the potential to expand their octet.
Alexander Hari 1L wrote:Elements in the 1st and 2nd period do not have access to the the d orbital which prevents them from having an expanded octet, therefore elements that are in the 3rd period and below have the potential to expand their octet.
What is the extent of an extended octet?
Allen Chen 1J wrote:Any elements with unfilled d orbitals can have expanded octet.
Wait so if an element has a d-orbital but it is filled (ie As = [Ar]3d104s24p3) then it can't have an extended octet? Does this mean that only the transition metals can have an extended octet?
I know for sure non-metals have expanded octets so definitely not only transition metals. In the review today the TA said anything group 3 and lower can have an expanded octet so I think that's the most important thing to know.
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