Answer;
Atomic number Tc = 43 , which is equivalent to the number of protons in nucleus.
Number neutrons = mass number - number of protons = 99 - 43 = 56 neutrons .
Number of electrons = number of protons - charge = 43 - (+7) = 36 electrons
Step-by-step explanation;
-Atomic number is the number of proton in the nucleus of an atom of a given element. Mass number is the total number of protons and neutrons in the nucleus of an atom. A neutral atom has equal number of protons and neutrons.
-Isotopes are atoms of the same element with the same atomic number but different mass number.