[HmKwok]

Hello,
I want ask for the reason for the following trend:
Bond strength of C-H: tertiary alkane < secondary alkane < primary alkane

[ufalynn88]

there is more electron density in the bonds with more carbons adjacent

[Shinji]

there is more electron density in the bonds with more carbons adjacent

Hello,

Can you explain a bit more? From what I read, stability increases from primary to secondary to tertiary. So does that not also mean bond strength increases from primary to tertiary?

Thank you

[Arctic-Nation]

there is more electron density in the bonds with more carbons adjacent

Hello,

Can you explain a bit more? From what I read, stability increases from primary to secondary to tertiary. So does that not also mean bond strength increases from primary to tertiary?

Thank you

The OP has it wrong, as C-H bond strength increases in the order primary < secondary < tertiary. This is due to the fact that (unsubstituted) alkyl groups are weakly electron donating, and, of course, more alkyl groups means higher electron density and stronger bonds.