Algonquin College Health Program Assessment (AC-HPAT) Practice Exam

What is the atomic number of an atom that has 17 protons?

1. 20

2. 17

3. 34

4. 75

The correct answer is: 17

The atomic number of an atom is defined as the number of protons found in its nucleus. Protons are positively charged particles, and the atomic number uniquely identifies an element on the periodic table. For the atom in question, having 17 protons means its atomic number is 17. This value directly corresponds to the element chlorine, which is in the 17th position on the periodic table. Therefore, the correct answer accurately reflects this fundamental definition in atomic structure. The other numbers listed do not represent the atomic number of any atom with 17 protons; they correspond to different elements with more protons in their nuclei. Thus, the understanding of atomic numbers is critical in identifying elements and understanding their properties within the context of chemistry.