Which of the following best describes what happens to an atom if the electrons in its outer shell are altered?

• A. The atom will change into a different element.
• B. The atom will always become radioactive.
• C. The atom may become an ion by gaining or losing charge.
• D. The atom's nucleus will split into smaller particles.

Answer: (C)

Verified step by step guidance

1. Understand that the identity of an element is determined by the number of protons in its nucleus, not by the electrons in its outer shell.
2. Recognize that changing the electrons in the outer shell affects the atom's charge but does not change the number of protons, so the element itself remains the same.
3. Recall that when an atom gains or loses electrons, it becomes an ion, which is an atom with a net positive or negative charge.
4. Note that becoming radioactive or having the nucleus split involves changes to the nucleus, which are unrelated to changes in the outer electrons.
5. Therefore, altering the electrons in the outer shell results in the atom becoming an ion by gaining or losing charge.