This is a (n,γ) nuclear reaction (neutron-gamma).
the number of protons and neutrons added together
We call these different "flavors" of an element the isotopes of that element.
isotopes
There are 118 neutrons in the element gold.
Neutrons. If the differ in electrons they are not neutral and if they differ in protons then they are no longer the same element as the number of protons determines the name of the element.
Isotopes of elements have different atomic mass'.
Elements are substances such as Hydrogen. It has 1 Proton, and 0-2 neutrons. Since the number of neutrons can vary, we call each form of Hydrogen an isotope. A hydrogen with no neutrons and a hydrogen with 1 nuetron are both still Hydrogens. We simply call one the Hydrogen-1 Isotope. An isotope is just a variation of an element as the element can have different numbers of neutrons. All isotopes of an element have the same number of protons, else itd be an isotope of another element.
there are 61 neutrons in a the element silver
If 4 neutrons were added to the nucleus of an original element, it would become an isotope of that element. Isotopes have the same number of protons (and thus the same atomic number) but differ in their mass due to the additional neutrons. This change can affect the stability of the nucleus, potentially making it radioactive if the neutron-to-proton ratio becomes unfavorable. The chemical properties of the element would remain largely unchanged since they are primarily determined by the number of protons.
neutrons
The element comes with 30 neutrons is iron. It also has 26 protons.
Isotopes.