An atom's atomic number represents the number of protons in its nucleus. The mass number of an atom is the sum of its protons and neutrons. To determine the number of protons, electrons, and neutrons in an atom with atomic number 50 and mass number 125, we can use the following information:
- Atomic number (Z): 50
- Mass number (A): 125
The atomic number tells us that the atom has 50 protons. Since atoms are electrically neutral, the number of protons must be equal to the number of electrons. Therefore, the atom also has 50 electrons.
To determine the number of neutrons, we subtract the atomic number (protons) from the mass number:
Number of neutrons (N) = Mass number (A) - Atomic number (Z) = 125 - 50 = 75
So, the atom with atomic number 50 and mass number 125 contains 50 protons, 50 electrons, and 75 neutrons.