Look at the location of elements A, B, C, and D in the following
periodic table:
(c) Which hydrides react with water to give H2 gas? Write a balanced net ionic equation for each reaction.

Verified step by step guidance

1. Identify the elements A, B, C, and D on the periodic table. Determine their group and period.
2. Recognize that elements in groups 1 and 2 (alkali and alkaline earth metals) typically form hydrides that react with water to produce hydrogen gas.
3. For each element that forms a hydride reacting with water, write the general reaction: MH_x + H_2O \rightarrow M(OH)_x + H_2, where M is the metal and x is the number of hydrogens in the hydride.
4. Convert the general reaction into a net ionic equation by removing spectator ions. For example, for a group 1 metal hydride, the net ionic equation is: MH + H_2O \rightarrow M^+ + OH^- + H_2.
5. Ensure the net ionic equations are balanced in terms of both mass and charge.

Key Concepts

Hydrides

Hydrides are compounds formed between hydrogen and another element. They can be classified into different types, such as ionic, covalent, and metallic hydrides. The reactivity of hydrides with water varies based on their composition; for instance, alkali metal hydrides typically react vigorously with water to produce hydrogen gas and a corresponding hydroxide.

Net Ionic Equations

A net ionic equation represents the chemical species that are involved in a reaction, excluding spectator ions that do not participate in the reaction. This type of equation is useful for simplifying reactions in aqueous solutions, allowing chemists to focus on the actual chemical changes occurring. To write a net ionic equation, one must first write the balanced molecular equation and then remove the spectator ions.

Reactivity of Elements in Water

The reactivity of elements with water is influenced by their position in the periodic table. Alkali metals and some alkaline earth metals readily react with water, often producing hydrogen gas and a hydroxide. Understanding the trends in reactivity, such as increasing reactivity down a group, is essential for predicting which hydrides will react with water to release hydrogen gas.