What is the function of the magnesium atom in a chlorophyll molecule?

Magnesium  play  an  important  role in  the  chlorophyll  of  the  plant  since  is  it  enable  the  plant to  be able  to  convert  light  into   energy.Magnesium is the  central  atom  of  the  porphyrin  ring  of  the   green  plant  pigment (the  chlorophyll.The  magnesium center defines  the  structure  of  chlorophyll  molecules.

Spontaneity tell us the direction of the reaction, but not how fast it goes. gibbs free energy brings together enthalpy, entropy and temperature in one easy formula. g = h - ts. and, finally the sign of delta g is always negative for a spontaneous reaction.