Protons: 43 Neutrons: 56
Work Step by Step
The atomic number, as shown by the periodic table, of Technetium is 43, meaning that there are 43 protons (the atomic number is the number of protons). Because it is Technetium-99, the atomic mass number of this isotope is 99 amu. Because both protons and neutrons weigh one amu while electrons are essentially weightless, this means that there must be 56 neutrons (43 protons+56 neutrons= 99 amu).