Because attraction of water molecules around an ion depends on. that ion's density of charge, smaller ions (and thus ions of greater ionic. potenti. al) attract more water molecules. The result is the. inverse. relationship. between non-hydrated radius and hydrated radius shown below.
[v. 5] In Hebron he reigned over Judah seven years and six months: and in Jerusalem he reigned thirty and three years over all Israel and Judah.   This would have made David 37 when he became king of all Israel. Do not get confused between 'Judah' and 'Israel': they are not the same.
In 2 Samuel 2:1 Though David knew he has been anointed by God to be king over Israel, and now Saul was dead, with his military power he would have went ahead to imposed himself on the people of Israel, but he would not do that, so he still enquired from God whether to go into the land of Judah or not.0 Ishbosheth Saul's son was forty years old when he began to reign over Israel, and reigned two years. But the house of Judah followed David. 11 And the time that David was king in Hebron over the house of Judah was seven years and six months.