NCFE Physical Science Practice Exam

The group of elements classified as alkali metals is found in Group 1A of the periodic table. These elements include lithium, sodium, potassium, rubidium, cesium, and francium. Alkali metals are characterized by having a single electron in their outermost shell, which they readily lose to form positive ions, resulting in their strong reactivity and the formation of alkaline hydroxides when they interact with water.

This distinctive property stems from their electron configuration, leading to trends such as increasing reactivity down the group. The reactivity of alkali metals increases as you move from lithium to francium, due to the decreasing ionization energy required to remove that outer electron. Their common characteristics also include low density, metallic luster, and the ability to conduct electricity and heat.

In contrast, the other groups mentioned correspond to different categories of elements. Group 2A consists of alkaline earth metals, which have two electrons in their outer shell. Group 18 contains noble gases, which are known for their lack of reactivity due to having full valence electron shells. Group 17 consists of halogens, which are highly reactive nonmetals with seven electrons in their outer shell. Understanding the properties and classifications of these groups is crucial in chemistry