Chelate is a derivative from the Greek word “chele” – meaning claw.
The function of a Chelate (organic complex) is to chemically combine the positive-charged cation (zinc, manganese, iron, copper, magnesium or calcium) with an organic, negative charged chelating agent. The organic molecule surrounds the positive charged metal and protects the new Chelated form of cation from chemical tie up in the soil – or in the fertiliser spray tank.
The following diagram shows the chemistry of chelation and the reason Chelated micronutrients resist chemical tie up from phosphate fertilisers and high pH soils.