CHEMISTRY help! What is a cathode?

Ok, consider two electrodes placed in a pot of impure water but not touching. Apply a voltage and a current flows around the circuit. The cathode is the electrode connected to the + of the power supply, te anode is the other side. So yes the Cathode is effectively negatively charged, and the anode is effectively positively charged. We have applied a voltage, and so the 'extra electrons' come from the electrodes themselves and the water. The applied Electric field is just encouraging them to gather in certain places and not others.