Book cover for Objective Chemistry for Engineering and Medical Entrance Examinations

Objective Chemistry for Engineering and Medical Entrance Examinations

K Rama Rao

ISBN #9789332541771

1st Edition

2,463 Questions

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12,716 Students Helped

Homework Questions

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Summary
Learning Objectives
Key Concepts
Example Problems
Explanations
Common Mistakes

Summary

Alkaline earth metals, located in Group IIA of the periodic table, include Be, Mg, Ca, Sr, Ba, and Ra. They are notable for forming basic, alkaline oxides found naturally as compounds like lime, strontia, and baryta. A key distinguishing factor within this group is radium, which is radioactive, setting it apart from its non-radioactive counterparts. These characteristics not only define their chemical behavior but also influence their practical applications in various industries.

Learning Objectives

1

Describe the classification and properties of alkaline earth metals in the periodic table.

2

Identify the elements belonging to the alkaline earth metals group and understand their placement in Group IIA and the s-block.

3

Explain the significance of basic, alkaline oxides, including examples such as lime, strontia, and baryta.

4

Differentiate between stable alkaline earth metals and the uniquely radioactive nature of radium.

5

Discuss real-world applications and implications of the chemical properties of alkaline earth metals.

Key Concepts

CONCEPT

DEFINITION

Alkaline Earth Metals

Elements found in Group IIA of the periodic table and the s-block, including Be, Mg, Ca, Sr, Ba, and Ra, known for forming basic, alkaline oxides.

Basic, Alkaline Oxides

Oxides that exhibit basic properties when dissolved in water, commonly found in the earth in compounds such as lime (calcium oxide), strontia (strontium oxide), and baryta (barium oxide).

Radium

A radioactive alkaline earth metal that stands out among its mostly non-radioactive counterparts, having unique scientific and industrial applications.

Example Problems

Example 1

Radium is placed at the bottom of alkaline carth metals. The clement should (1) have the highest atomic volume (2) possess the minimum dcnsity (3) be less casily ionizable (4) be least clectropositive

Example 2

Radium is placed at the bottom of alkaline carth metals. The clement should (1) have the highest atomic volume (2) posscss the minimum density (3) be less casily ionizable (4) be least clectropositive

Example 3

Magnesium form $\mathrm{Mg}^{2 \prime}$ and not $\mathrm{Mg}$ becausc (1) Magncsium carbonate is insolublc in water. (2) Gcnerally higher oxidation states are prefcrred by metals. (3) Ionic radius of $\mathrm{Mg}$ (II) is smaller than $\mathrm{Mg}$ (I). (4) IIydration cnergy of divalent magnesium ion is higher.

Example 4

Magnesium form $\mathrm{Mg}^{21}$ and not $\mathrm{Mg}$ because (1) Magncsium carbonate is insolublc in watcr. (2) Gcnerally higher oxidation states are preferred by metals. (3) Ionic radius of $\mathrm{Mg}$ (II) is smaller than $\mathrm{Mg}$ (I). (4) IIydration cnergy of divalent magnesium ion is higher.

Example 5

A chloride dissolves appreciably in cold water. When placed on a platinum wire in bunsen flame no distinctive colour is noticed. Based on the information provided, which one is a cation? (1) $\mathrm{Mg}^{2}$ (2) $\mathrm{Ba}^{21}$ (3) $\mathrm{Pb}^{2}$ (4) $\mathrm{Ca}^{2+}$
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Step-by-Step Explanations

QUESTION

List the alkaline earth metals and explain why radium is uniquely classified within this group.

STEP-BY-STEP ANSWER:

Step 1: Identify the members of Group IIA in the periodic table, which are Be, Mg, Ca, Sr, Ba, and Ra.
Step 2: Recognize that these elements are part of the s-block, indicating their electron configuration and similar chemical behavior.
Step 3: Explain that they are called 'alkaline earth metals' because they form basic (alkaline) oxides, such as lime (calcium oxide), strontia (strontium oxide), and baryta (barium oxide) naturally occurring in the earth.
Step 4: Note that while most of these elements are non-radioactive, radium is distinctly radioactive, which affects its applications and handling.
Final Answer: The alkaline earth metals are Be, Mg, Ca, Sr, Ba, and Ra, with radium being unique due to its radioactivity, distinguishing it from the other stable, non-radioactive members.

Identifying Alkaline Earth Metals and Their Characteristics

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Common Mistakes

  • Confusing alkaline earth metals with alkali metals found in Group IA, despite their different properties and placements in the periodic table.
  • Overlooking the significance of the 'basic, alkaline oxides' terminology, which explains why these metals are named as such.
  • Failing to recognize the unique aspect of radium's radioactivity compared to the other alkaline earth metals.
  • Assuming all alkaline earth metals exhibit uniform properties without considering the variations among individual elements.