Why is there a greater degree of separation in a dipole-dipole interaction?

My textbook says this:



> 
> Electrostatic forces between two ions decrease by the factor $\frac{1}{d^2}$ as their separation distance, $d$, increases. Dipole–dipole forces, however, vary as $\frac{1}{d^4}$. Because of the higher power of $d$ in the denominator, the attractive forces diminish with increasing $d$ much more rapidly than does $\frac{1}{d^2}$. As a result, dipole forces are effective only over very short distances.
> 
> 
> 


Now mathematically I understand why this is true, but I don't understand why this is the case in reality. Can someone shed some light on this?




Like I answered my other question, this is in some ways very similar. Since electrostatic attractions are so strong, it is decreases less at a longer distances. The $+$ & $-$ are attracted together so strongly. 


Dipole-dipole attractions aren't strong attractions, electrostatic attractions are stronger, since they are created by ionic bonding. Dipole-dipole occur in covalent bonding. Thus dipole-dipole attractions decrease with increasing distance faster.


This is just a piece of the whole picture.




---


Check the refs: [1](https://en.wikipedia.org/wiki/Intermolecular_force), [2](https://www.chem.purdue.edu/gchelp/liquids/dipdip.html), [3](http://chemed.chem.purdue.edu/genchem/topicreview/bp/intermol/intermol.html). They provide more in depth detail to the entire picture.


 2

Imagine the dipole as a partial positive ($q\_+$) and negative ($q\_-)$ separated by a small distance $\delta$. The electrostatic potential due to the dipole is $\frac{q\_+}{|d-\delta|}+\frac{q\_-}{|d+\delta|}$ where $d$ is the distance to the midpoint between the two charges. (There is also an angle term which I left out for simplicity).


As $d$ increases $\frac{q\_+}{|d-\delta|}\approx -\frac{q\_-}{|d+\delta|}$, i.e. the electrostatic potential of the dipole (i.e. two very close charges of opposite charge) goes to zero faster than a single charge because at longer distances the two charges appear to be at the same position and "cancel each other out".


[Feynman has given as a more thorough explanation](http://www.feynmanlectures.caltech.edu/II_06.html#Ch6-S2). 


 2