To solve this problem, let's go through a step-by-step analysis:
1. Understanding Atomic Number: The atomic number ([tex]\( Z \)[/tex]) of an element is the number of protons present in the nucleus of an atom of that element. This number is a fundamental property that defines the element and does not change in a normal chemical reaction.
2. Cation Formation: When an atom loses electrons, it becomes a cation. A tripositive cation means that the atom has lost 3 electrons.
3. Electrons vs. Protons: While the number of electrons in a neutral atom is equal to the number of protons (atomic number, [tex]\( Z \)[/tex]), the number of protons (atomic number) in the nucleus does not change when an atom loses or gains electrons to form ions.
4. Effect on Atomic Number: The atomic number of an atom remains the same regardless of the ionization state (neutral atom, cation, or anion). Therefore, even after losing 3 electrons to become a tripositive cation, the number of protons, and hence the atomic number, remains unchanged.
Given this understanding, the correct answer to the question "If a metal with atomic number [tex]\( Z \)[/tex] is converted to a tripositive cation then its atomic number will become:" is:
(3) [tex]\( Z \)[/tex]
