Final answer:
Changing the number of neutrons in a copper atom creates isotopes with similar chemical properties but potentially different physical properties. Altering the number of electrons results in copper ions with different charges and characteristics, while the number of protons determines the atomic identity as copper.
Step-by-step explanation:
When considering how changing the number of each particle affects the characteristics of a neutral atom of copper, it's essential to understand the role of protons, neutrons, and electrons within an atom. For a neutral copper atom, the number of protons (which defines the element as copper) must equal the number of electrons to balance the charge. Change in the number of neutrons can lead to different isotopes of copper, which may have slightly different physical properties but retain the same chemical behavior.
Changing the number of electrons will alter the atom's charge, transforming a neutral atom into an ion. If electrons are added to a copper atom, it will become negatively charged, and if electrons are removed, it will become positively charged. These ions exhibit different chemical and physical properties because the balance between protons' positive charge and electrons' negative charge is disrupted.