Final answer:
Atoms gain or lose electrons to achieve a stable noble gas electron configuration, resulting in the formation of ions. Cations are positively charged ions formed by metals losing electrons, while anions are negatively charged ions formed by nonmetals gaining electrons. The atomic number remains unchanged during this process.
Step-by-step explanation:
Atoms of an element tend to gain or lose electrons in order to have the same number of outer orbital electrons as a noble gas, as stated in option C. This is known as achieving a noble gas configuration, which is the most stable electronic arrangement for an atom. Atoms can gain or lose electrons and become ions, acquiring a positive or negative charge. This process is called ionization.
When an atom loses electrons, it forms a cation, which is positively charged due to having more protons than electrons. Metals typically form cations by losing electrons. On the other hand, when an atom gains electrons, it becomes an anion, which is negatively charged. Nonmetals often form anions by attaining extra electrons to fill their outer shell.
It's important to note that while the number of electrons changes during ion formation, the type of element remains the same since the atomic number (which is determined by the number of protons) does not change.