If you look at the structure of ATP, below, you have three phosphates (P) at 5'C, a ribose (R), and adenosine (A).
P--P--P--5'R1'--A
Charge repulsion occurs between the oxygen atoms. Due to electronegativity, the oxygen atom is partially negative, so having 10 oxygen atoms in close proximity, charge repulsion will occur.
Resonance occurs between the oxygen atoms.
[O=P-O-P... <---> (-)O-P=(+)O-P-....]
This is not a great model, but you can see + and - charges on the individual oxygen atoms.
Resonance allows for electron distribution which leads to charge repulsion.
Hydrolysis of ATP.
Due to resonance and charge repulsion, the energetics of hydrolysis becomes favorable. Removing charge repulsion which each P removed.
