Anions and Cations are negative and positively charged ions (Molecules) that are dissolved in the water. Water conducts electricity better when there are salts dissolved in the water.
Different types of metals placed close to each other also conduct electricity between the atoms of the metals. A current forms between to different metals that are placed in contact with each other. Thermocouples are made based on this principle. As the temperature gets warmer more electrons flow from one metal to the other and more current is produced.
The Zinc Anode is there to protect the motor's metal. Zinc is more reactive that other metals (Steel) and it's sacrificed first to protect your motor. ie the zinc ions are dissolved in the water instead of the steel or iron metal.
It's all about the number of electrons in the outer orbits of the atoms. Some atoms have a more stable number or electrons and others need another electron to become stable. While other atoms want to give up an extra electron to become more stable.
Your hot water heater also has a zinc anode that does the same thing inside your hot water heater.
Originally Posted by boxingref_rick