What is the element's atomic number in Periodic Table Group 17 and Periodic Period 3?

17

The correct answer is option 3. 17.

In the periodic table, elements are organized into rows called periods and columns called groups. Each element is uniquely identified by its atomic number, which represents the number of protons in the nucleus of its atoms.

Group 17 of the periodic table is known as the halogens. These elements include fluorine \((F)\), chlorine \((Cl)\), bromine \((Br)\), iodine \((I)\), and astatine \((At)\). These elements are highly reactive nonmetals and share similar chemical properties.

Period 3 of the periodic table is the third row from the top. This period includes elements from sodium \((Na)\) with atomic number 11 to argon \((Ar)\) with atomic number 18. Therefore, the element in Group 17 and Period 3 is chlorine \((Cl)\), which has an atomic number of 17.

Chlorine is a diatomic molecule, meaning it exists naturally as \(Cl_2\) gas. It is a highly reactive, greenish-yellow gas with a pungent odor. Chlorine is widely used in various applications, including water treatment, disinfectants, bleach production, and the manufacture of numerous chemicals.

In summary, the element in Group 17 and Period 3 of the periodic table is chlorine, with an atomic number of 17.