To which third period element do these ionization values belong?

IE1 = 578 kJ/mol 

IE2 = 1820 kJ/mol 

IE3 = 2750 kJ/mol 

IE4 = 11600 kJ/mol

If the following set of successive ionization energies are your ionization values this would likely belong to Aluminum. Since there is a huge point between the third and fourth ionization energies, which designates that the atom reached noble gas configuration after the third electron was removed. The element which has 3 valence electrons in the third period is aluminum.

14 days is the half-life of phosphorus-32