Ace Your MCAT 2025: Conquer General Chemistry with Confidence!

Alkali metals, which are found in Group 1 of the periodic table (such as lithium, sodium, and potassium), consistently exhibit an oxidation number of +1. This is because alkali metals have one electron in their outermost shell. During chemical reactions, these metals tend to lose this single valence electron in order to achieve a stable electron configuration, resembling that of the nearest noble gas.

When they lose their one valence electron, alkali metals become cations with a charge of +1. This behavior is seen across all alkali metals, making +1 their characteristic oxidation state. This consistent pattern is fundamental to understanding many chemical reactions and properties involving alkali metals, as they readily react with nonmetals, often forming ionic compounds.

Other choices reflect oxidation states that do not align with the typical behavior of alkali metals, as they do not lose two electrons or gain electrons to achieve negative oxidation states under standard conditions.