Mosfet as switch Arduino 36V 1.5A
You are well within Worst Case Limits for Vgs.



It only means the higher your Vgs the lower the RdsOn 


At some point between Vgs=1 to 2.5 Vds will start to conduct heavily.

So with Vgs=5V you can expect RdsOn &lt;= 0.05 Ohm