The atomic number represents the number of protons in an atom. In this case, the atomic number is 6, which means the number of protons is also 6.
The mass number of an atom is the sum of the protons and neutrons in the nucleus. To find the mass number, you can add the number of protons (6) and the number of neutrons (15) together. Therefore, the mass number is 21 (6 + 15 = 21).
In a neutral atom, the number of electrons is equal to the number of protons. Since the number of protons is 6, the number of electrons is also 6.
To summarize:
- Atomic number (number of protons) = 6
- Mass number (number of protons + number of neutrons) = 21
- Number of electrons = 6