Final answer:
A cobalt (Co) atom contains 27 protons, which is its atomic number, and in a neutral state, it also has 27 electrons. The number of neutrons can vary in cobalt depending on the isotope.
Step-by-step explanation:
An atom of cobalt (Co) contains 27 protons. This number is also the atomic number of cobalt, which identifies the element and determines its place on the periodic table. Neutral atoms have the same number of protons and electrons, so a neutral cobalt atom also has 27 electrons. As for neutrons, they can vary because of the different isotopes of cobalt, but for example, an isotope of cobalt with a mass number of 57 would have 30 neutrons (mass number = protons + neutrons, so 57 = 27 protons + 30 neutrons).