What happens when metals from the lanthanoid group react with water?

When metals from the lanthanoid group react with water, they typically produce hydrogen gas. Lanthanoid metals, which are a series of 15 metallic elements in the periodic table from lanthanum to lutetium, tend to have varying reactivities with water depending on their specific properties. Generally, when these metals come into contact with water, they undergo a chemical reaction that involves the formation of hydroxides and the evolution of hydrogen gas.

This production of hydrogen is indicative of a metal's ability to displace hydrogen from water, which is characteristic of many metals. The hydroxides formed are usually insoluble or only slightly soluble in water, contributing to the formation of a precipitate in some cases.

In contrast, while some lanthanoids may act as reducing agents in certain reactions, and they do form salts when they react with other compounds, these behaviors do not specifically address their reaction with water. Additionally, it is incorrect to state that they do not react with water; most lanthanoid metals do indeed react with it under appropriate conditions, leading to the generation of hydrogen gas. Thus, the correct response highlights the specific outcome of the reaction between these metals and water, focusing on the production of hydrogen gas.