Bond Strength Clarification

[Samiha Molla 3G]

Hi I just wanted to clarify how the strengths of bonds relate to atomic/molecular size.
For two atoms interacting, is the bond stronger and shorter between two small atoms and weaker and longer between two larger atoms? And would the opposite be true for molecules - two large molecules would have stronger bonds since there is more surface area for interaction between the electron densities?

[Marisa Gaitan 2D]

The bond is stronger between two smaller atoms and weaker between two larger atoms because the bonds get longer as the size of the radius in each atom increases. (Longer bonds result in weaker bonds). The opposite is true for molecules: larger molecules will have stronger intermolecular forces (to prevent myself from getting confused, I don't really think of them as bonds but more like attractive forces) and therefore tend to form liquids and solids because these forces are stronger. Lavelle had a good example of this in his lecture today (11/11) where he showed substances of larger molecules such as octadecane (C18H38) forming waxy solids as opposed to pentane (C5H12) which was a runny liquid.

[Audra Mcleod 3G]

Hello!
Yes, bonds between larger atoms are longer and weaker as compared to bonds between smaller atoms, due to the fact that the increased atomic radii of these large atoms prevents them from coming into close contact with one another. In regards to molecules, I'd also assume that larger molecules would correspond to a stronger bonds since, as Lavelle mentioned today, the attraction of dispersion forces increases between larger, heavier molecules since they are more polarizable.

[Samiha Molla 3G]

thank you!

[Brett Lieuallen 2A]

On this topic, would ionic bonds with longer bond lengths be stronger than shorter bonds in water since it possesses a bit of a covalent character?

[Nhu Pham-Dis3G]

When two atoms are larger the bonds are weaker because they are not as close to each other. Likewise, when two atoms are smaller the bonds are stronger because they are closer together!