Answer :
Final answer:
The periodic table groups elements by reactivity, including alkali metals, alkaline earth metals, pnictogens, chalcogens, halogens, and noble gases, due to their identical valence shell electron configurations.
Explanation:
In the periodic table, elements that react similarly to each other are arranged in groups or families. This includes groups such as alkali metals (group 1), alkaline earth metals (group 2), pnictogens (group 15), chalcogens (group 16), halogens (group 17), and noble gases (group 18). The similar reactivity within a group is due to the identical number and distribution of electrons in the valence shells of the elements.
Elements in the same group have the same number and distribution of electrons in their valence shells, leading to similar chemical properties. These elements can be categorized as metals, nonmetals, and metalloids, or more specifically as main-group elements, transition metals, and inner transition metals.
Groups 1 and 2 are named alkali and alkaline earth metals, and they typically lose electrons in reactions. As you descend within a group, the metallic characteristics of the atoms become more pronounced, leading to varying reactivity patterns within the same group.
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