Final answer:
A chromium (Cr) atom has 24 protons, 24 electrons, and 28 neutrons, calculated by subtracting its atomic number from its mass number.
Step-by-step explanation:
The element chromium (Cr) has an atomic number of 24, which means it has 24 protons in its nucleus and, when neutral, it also has 24 electrons. The mass number of chromium is given as 52, which is the sum of its protons and neutrons. To calculate the number of neutrons, we subtract the atomic number (number of protons) from the mass number:
52 (mass number) - 24 (atomic number) = 28 neutrons
Therefore, a chromium atom has 24 protons, 24 electrons, and 28 neutrons in its nucleus.