To determine the number of protons, electrons, and neutrons in an atom, we need to understand the atomic number and mass number.
The atomic number (Z) represents the number of protons in an atom. In this case, the atomic number is given as 50, so the atom contains 50 protons.
The mass number (A) represents the total number of protons and neutrons in an atom. It is usually denoted as a superscript before the chemical symbol of the element. Here, the mass number is given as 125.
To calculate the number of neutrons, we subtract the number of protons (atomic number) from the mass number:
Number of neutrons = Mass number (A) - Atomic number (Z)
Number of neutrons = 125 - 50 = 75 neutrons
Since atoms are electrically neutral, the number of electrons is equal to the number of protons. Therefore, in this atom, there are also 50 electrons.
In summary, the atom with an atomic number of 50 and a mass number of 125 contains 50 protons, 50 electrons, and 75 neutrons.