Zinc has the chemical symbol Zn and the atomic number 30. How many protons, neutrons, and electrons does an atom of zinc-69 have?

A. 30 protons, 39, neutrons, 39 neutrons

B. 39 protons, 30 neutrons, 30 neutrons

C. 39 protons, 30 neutrons, 39 electrons

D. 30 protons, 39, neutrons, 30 electrons

D, because isotopes all have the same atomic number but different number of neutrons

D. 30 protons, 39 neutrons, 30 electrons

Explanation:

The atomic number (Z) is the number of protons (p) in the nucleus. Since

Z = 30, p = 30.

In a neutral atom, the number of electrons (e) equals the number of protons. Since p = 30, e = 30.

The mass number (A) is the number of protons plus the number of neutrons (n).

A = p + n

For an atom of zinc-69,

69 = 30 + n Subtract 30 from each side and transpose

n = 39