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.
David was the eighth and youngest son of Jesse from the kingly tribe of Judah. He was also a direct descendent of Ruth the Moabite. David began his life as a shepherd in Bethlehem. One day, the prophet Samuel called him out of the field and anointed him without the knowledge of the current king, Saul. David simply returned to his sheep.