Two elements whose symbols are derived from the first and third letter of the name are _____ and ______
Chlorine is an element having the symbol Cl and this symbol is derived from the first and third letters of the name.
Magnesium is an element having the symbol Mg and this symbol is derived from the first and third letters of the name.
So, Two elements whose symbols are derived from the first and third letter of the name are Chlorine and Magnesium.