Final answer:
The assertion that hydrogen can behave like a metal or a nonmetal is true, thanks to its unique properties and bonding capabilities. It can form both cations and anions, reflecting its ability to act like elements in both group 1 and group 17 of the periodic table.
Step-by-step explanation:
The statement that hydrogen can act as either a metal or a nonmetal is true. Hydrogen's unique position on the periodic table allows it to have properties similar to both group 1 alkali metals, wherein it can lose an electron to form a cation H+, and group 17 halogens, where it can gain an electron to form a hydride ion, Hˉ, or share an electron through covalent bonding. Although it is in group 1, hydrogen is not considered an alkaline earth metal; instead, it is a nonmetal and exhibits distinct properties.
Due to the uniqueness of hydrogen, which only requires two electrons to fill its valence shell, it often follows the duet rule, forming one bond to achieve a stable electronic configuration. The fact that hydrogen's chemistry allows it to form ionic hydrides, take part in covalent bonding, and react in various ways with other elements reinforces its distinctive nature among the elements.