Question #c9c99

1 Answer
Dec 7, 2014

That's a good question. Many of the elements have isotopes, but there also a few elements that have no isotopes:
The elements with no isotopes are listed here:

Beryllium-9
Fluorine-19
Sodium-23
Aluminum-27
Phosphorus-31
Scandium-45
Manganese-55
Cobalt-59
Arsenic-75
Yttrium-89
Niobium-93
Rhodium103
Iodine-127
Cesium-133
Praseodymium-141
Terbium-159
Holmium-165
Thulium-169
Gold-197
Bismuth-209
(source:http://digipac.ca/chemical/molemass/isotope1.htm)

The numbers represent the protons+neutrons which come extremely close to the atomic mass.