Final answer:
The atomic symbol for the isotope with a mass number of 72 and an atomic number of 33 is 72₃₃As, representing the element arsenic (As).
Step-by-step explanation:
The atomic symbol for an atom with a mass number of 72 and an atomic number of 33 is As. This is because the atomic number corresponds to the element's position on the periodic table, which for 33 is arsenic (As). The mass number, which is the total number of protons and neutrons in the atom's nucleus, is represented as a superscript to the left of the element symbol. Thus the atomic symbol for this isotope of arsenic is written as 7233As.