This question already has an answer here:
I'm not a chemistry expert and merely a high school student. In my book there is a slight introduction to VSEPR theory and therein they mention that lone pair-lone pair repulsions are maximum, followed by lone pair-bond pair and then bond pair-bond pair repulsions.
Now the reasoning they provide to this is that as lone pairs are localized on the central atom, and each bond pair is shared, the lone pair occupies more space and hence the repulsions are greater.
Now I don't understand how localisation of lone pair leads to its large size and secondly what is meant by"size"here, because it's hard to imagine size of a lone pair for me.
It's a request not to mention about advanced theories like molecular orbital theory, because I'm not familiar with aaj that right now.
EDIT I would say that the other is also in a way similar but I could not find an answer of my question there. That's why I posted it.
Any of your help is appreciated.