why is salt more effective than sugar in lowering water activity?

All the webby kept saying that salt have higher water binding capacity.. but doesn't states why.. I've been searching the net for like an hr.

cause a+ binds to 6 H20 and Cl- binds with 5.. and they are ionic bond... that's what i find out only.. but how to compare with sucrose?

think about the amount of charge on NaCl and the sizes of the ions, then try the same with sucrose. Look up charge density.

.. and they are ionic bond...

and which is different from the bond existing in sucrose

There are a lot more ions in a gram of salt than molecules in a gram of sugar.