Comments on: Sigma bonds come in six varieties: Pi bonds come in one

By: Sigma bonds come in six varieties: Pi bonds come in one | Straight A Mindset

Tue, 17 Oct 2023 23:28:27 +0000

[…] General principle – the more s character the bond has, the more tightly held the electrons will be. [Note 1] […]

By: Orbital Hybridization And Bond Strengths | Straight A Mindset

Orbital Hybridization And Bond Strengths | Straight A Mindset — Tue, 17 Oct 2023 23:23:31 +0000

[…] Recognizing the type of bonds in molecules is a key skill. (see also: C-C sigma bonds come in six varieties, C-C pi bonds come in one). […]

By: James Ashenhurst

James Ashenhurst — Wed, 14 Dec 2022 04:05:18 +0000

In reply to Joshua Weland.

The key is to keep one variable constant while the other changes.

For example in the first 3 cases, one side is sp3, while the other side goes from sp3 to sp2 to sp. With increasing s-character we should expect (and we do see) a strengthening of the bond as shown by the decreasing bond length.

For the next two examples we are keeping the right-hand side constant (sp2) while increasing the s-character of the left hand side (sp2 to sp) and we again see a decrease.

It would be unfair to be asked to guess whether sp3-sp is stronger/shorter than sp2-sp2 because we are changing both sides at the same time and it is difficult to predict the outcome.

A fair question would instead keep one side constant and change the other side in a linear fashion.

By: Joshua Weland

Joshua Weland — Tue, 06 Dec 2022 21:32:23 +0000

I am a bit confused by the representative bond length table, as it is listed in almost increasing bond length with the exception of the swap of sp-sp3 and sp2-sp2. Although the different is only 1pm I presume there are other factors affecting the bond length between 2 specific elements, hence the “representative bond length table”. Given 2 arbitrary elements that can take the either the sp, sp2, sp3 hybridization will the ranking of their bond lengths always follow table’s representative bond lengths?

The reason I ask this is Quiz #679 as the ranking of the bond lengths would follow this table if it were in order, neglecting the actual numerical values, otherwise would the solution not be incorrect?

By: Nidhi Sharma

Nidhi Sharma — Tue, 18 May 2021 11:18:17 +0000

Thanks for this amazing explanation...

By: James Ashenhurst

James Ashenhurst — Wed, 18 Sep 2019 17:59:18 +0000

In reply to moneesh. C-H (sp3) : 1.50 Angstroms. C-H (sp2) 1.40 Angstroms. C-H (sp) 1.30 Angstroms.

By: James Ashenhurst

James Ashenhurst — Fri, 13 Sep 2019 16:24:33 +0000

In reply to alina.

Hi Alina – “s” character refers to hybrid orbitals. An sp3 hybrid orbital is made of 1 s orbital and 3 p orbitals, so it has 25% s character and 75% p character.
An sp2 hybrid orbital is made of one s orbital and 2 p orbitals so it has 33% s character and 66% p character.
An sp hybrid orbital is made from 1 s orbital and 1 p orbital so it has 50% s character and 50% p character.

By: James Ashenhurst

James Ashenhurst — Thu, 12 Sep 2019 20:56:05 +0000

In reply to zoramtharmawia. More s-character means the electrons are held tighter to the nucleus, which means a shorter bond length. In an sp-hybridized C-H bond the electrons have 50% s-character and will be held closer to the nucleus than in sp2 C-H (33%) and sp3 C-H (25%).

By: James Ashenhurst

James Ashenhurst — Wed, 21 Aug 2019 17:59:27 +0000

In reply to Sangeeth. The bond dissociation energy of a C-C single bond is generally about 80 kcal/mol. The bond dissociation of a C-C pi bond is generally about 60 kcal/mol. The pi bond is weaker than the sigma bond.

By: James Ashenhurst

James Ashenhurst — Mon, 08 Apr 2019 15:57:03 +0000

In reply to Jesse Linares. Awesome, thanks for letting me know Jesse!