Problem 19 - A Complete Resource Book in Chemistry for JEE Main

Question

As the alkaline earth metals (except Be) tend to lose their valence electrons readily, they act as (a) bases (b) strong reducing agents (c) weak oxidizing agents (d) weak reducing agents

Step-by-Step Solution

Answer

(b) strong reducing agents.

Step 1: Identify Alkaline Earth Metals

Alkaline earth metals include beryllium, magnesium, calcium, strontium, barium, and radium. Except for beryllium, these elements have two electrons in their outermost shell.

Step 2: Understand Electron Loss

Alkaline earth metals tend to lose their two valence electrons easily to achieve a stable electron configuration, resembling the nearest noble gas.

Step 3: Reducing Agent Definition

A reducing agent donates electrons to another element or compound, allowing the other substance to be reduced. As alkaline earth metals lose electrons easily, they act as reducing agents.

Step 4: Evaluate Strength of Reducing Agents

The readiness to lose electrons implies that the alkaline earth metals, especially those heavier than beryllium, act as strong reducing agents.

Step 5: Select Correct Option

Among the given choices, strong reducing agents best describe the chemistry of alkaline earth metals (except Be) as they readily lose valence electrons.

Key Concepts

Reducing Agents

Alkaline earth metals, with the exception of beryllium, are well-known for their role as reducing agents. But what are reducing agents, and why do these metals fit the bill? In chemical reactions, a reducing agent donates electrons to another substance, thus enabling the latter to undergo reduction. When an element acts as a reducing agent, it loses electrons—this is where alkaline earth metals shine. They have a high tendency to donate their valence electrons, encouraging other elements to gain them. This is especially true for heavier alkaline earth metals like magnesium and calcium. - **Heavier metals**: The further down the periodic table you go in the alkaline earth metals group, the more energy-efficient the electron donation process becomes. - **Strong reducers**: Metals like magnesium and calcium are considered strong reducing agents because of their enthusiasm to shed electrons quickly and easily.
Therefore, in many reactions, particularly those involving oxidizing agents, alkaline earth metals act as powerful companions in electron transfer.

Valence Electrons

In any chemical element, valence electrons play a critical role because they are the outermost electrons involved in forming chemical bonds. Alkaline earth metals, excluding beryllium, typically have two valence electrons. These electrons are on standby, ready to take part in chemical interactions. - **Two electrons to lose**: The presence of two valence electrons makes these metals highly motivated to lose them in order to achieve a more stable, noble gas electron configuration. - **Reactivity connection**: This tendency to lose electrons relates directly to their reactivity. The willingness to part with these electrons is what makes them such potent reducing agents.
By parting with their valence electrons, alkaline earth metals can stabilize, mimicking the noble gas configuration and ensuring effective participation in chemical reactions.

Electron Configuration

Understanding electron configuration is essential to grasp why alkaline earth metals behave the way they do in chemical processes. So, what is an electron configuration?Electron configuration denotes the arrangement of electrons in the orbitals of an atom. For alkaline earth metals, their configuration ends with an "s" orbital.- **Examples**: - Magnesium: The electron configuration for magnesium is given as \[1s^2 2s^2 2p^6 3s^2\] This means magnesium has two electrons in its outermost "3s" orbital, which are the valence electrons. - Calcium: Similarly, calcium has the electron configuration of \[1s^2 2s^2 2p^6 3s^2 3p^6 4s^2\] Here, the two electrons in the "4s" orbital are ready for interaction.This configuration is key because having two electrons in the outer shell is a characteristic trait of alkaline earth metals, making them eager participants in forming stable and reactive compounds by losing these electrons.