Which group of elements are known as alkali metals?

Alkali metals are indeed classified as reactive metals that reside in Group 1 of the periodic table. This group includes elements such as lithium, sodium, potassium, rubidium, cesium, and francium. One of the key characteristics of alkali metals is their tendency to lose a single electron from their outermost shell, which makes them highly reactive, particularly with water and halogens. Their reactivity increases as you move down the group due to the decreasing ionization energy, allowing these metals to easily form positive ions.

In contrast, the other groups mentioned in the options represent different categories of elements, such as alkaline earth metals in Group 2, transition metals in the central block, and halogens in Group 17, none of which share the distinct properties of the alkali metals. Hence, recognizing alkali metals by their position in Group 1 is essential in understanding their chemical behavior and reactivity. This foundational knowledge is crucial for predicting their interactions in various chemical contexts.