How can iodine (Z = 53) have a higher atomic number yet a lower atomic mass than telluriurn (Z = 52) ?

Iodine have higher atomic size than tellurium because of the presence of more number of protons and lower atomic mass than tellurium because of the presence of lower number of neutrons.

Explanation:

Atomic number of an element is the number of the protons present in the element.

Atomic mass is the sum of a protons and the neutrons which are present in the nucleus of the atom.

Iodine has higher atomic number than tellurium because it has more number of protons than the tellurium.

On the other hand, iodine has lower atomic mass than tellurium because it has less number of neutrons in its core.