Which of the following are Group 1 elements?

• A. Halogens
• B. Noble Gases
• C. Alkali Metals
• D. Transition Metals

Answer: (C)

Group 1 elements are the alkali metals. They sit in the first column of the periodic table and each has one electron in its outermost shell, which makes them highly reactive and gives them a +1 oxidation state in compounds. They’re soft metals with low densities and melting points relative to many other metals, and they react vigorously with water to form hydrogen gas and metal hydroxides. Because of how reactive they are, they’re typically stored under oil to prevent air and moisture from triggering reactions. These traits set them apart from the other groups listed: halogens are Group 17 and nonmetals that gain an electron, noble gases are Group 18 with full valence shells and are very unreactive, and transition metals occupy the middle of the table with multiple oxidation states.