Problem 52 - 43 Years JEE ADVANCED (1978-2020) + JEE MAIN Chapterwise & Topicwise Solved Papers Chemistry

Question

True/ False The basic nature of the hydroxides of group 13 (Gr. III B) decreases progressively down the group.

Step-by-Step Solution

Answer

False. The basic nature increases down Group 13.

Step 1: Understand Group 13 Elements

Group 13, also known as Group III B, consists of the elements boron (B), aluminum (Al), gallium (Ga), indium (In), and thallium (Tl). The hydroxides of these elements are B(OH)₃, Al(OH)₃, Ga(OH)₃, In(OH)₃, and Tl(OH)₃.

Step 2: Recognize the Trend in Acidity and Basicity

Within any group of elements in the periodic table, the basicity of hydroxides is influenced by the metallic nature of the elements. As you move down a group, the elements tend to become more metallic, thereby increasing the basic character of their hydroxides.

Step 3: Apply the Trend to Group 13

In Group 13, boron is a non-metal, while the other elements are metals. As we move down the group from boron to thallium, the metallic character increases, and thus the hydroxides become more basic. Therefore, B(OH)₃ is weakly acidic, and the hydroxides become increasingly basic down the group.

Step 4: Conclusion Based on the Trend

Since the hydroxides become more basic as we move down Group 13, it is incorrect to state that the basic nature decreases as you move down the group. The statement is false.

Key Concepts

Basicity of Hydroxides

The basicity of hydroxides is an interesting topic when exploring periodic trends, especially for the elements of Group 13 in the periodic table. Hydroxides are compounds that contain the hydroxide ion \( ext{OH}^- \). The basic nature refers to the ability of a hydroxide to neutralize acids.

In Group 13, the common hydroxides are B(OH)₃, Al(OH)₃, Ga(OH)₃, In(OH)₃, and Tl(OH)₃. Each of these hydroxides has different levels of basicity. This means they react differently with acids due to the variation in their chemical structure and the metallic nature of the element they are derived from.

• Hydroxides of non-metals, like boron, tend to be less basic and sometimes even acidic.
• Conversely, hydroxides of metals express stronger basic characteristics.

Understanding the reason behind these differences is key to mastering the concept of hydroxide basicity. This character is influenced by the electron structure of elements;more positively charged metallic elements can attract the hydroxide ions more strongly, boosting their ability to neutralize acids.

Periodic Table Trends

Periodic table trends are essential for understanding chemical behavior and properties of elements. This system organizes elements according to increasing atomic number, helping us predict how elements will react with each other.

For Group 13, the general trend from top to bottom is a gradual increase in metallic character. Boron is a metalloid with properties of both metals and non-metals, while aluminum, gallium, indium, and thallium are considered metals.

• As you move down a group in the periodic table, atomic size increases due to the addition of electron shells.
• Another trend is the increasing metallic character of the elements because outer electrons are more loosely held.

These trends directly influence the chemical properties, like basicity of hydroxides. With increasing metallic character, the hydroxides of these elements generally shift towards more basic behavior. Recognizing these trends provides a critical foundation for chemistry studies.

Metallic Nature

Metallic nature is an important concept that influences how elements react in various chemical contexts. Metallic character refers to how easily an element can lose electrons, a property that is strongly linked to the element's position on the periodic table.

Elements in Group 13 show a distinct change in metallic nature from top to bottom in the group.

Boron, at the top of Group 13, is a non-metal and tends to gain electrons in reactions, exhibiting weak metallic characteristics. As you move down the group, you encounter aluminum, gallium, indium, and thallium, which all show a greater tendency to lose electrons and form cations.

• Increased electron loss signifies increased metallic character.
• This shift influences their hydroxides, making them more basic as metallic character increases.

Understanding metallic nature helps us grasp how these hydroxides behave differently and plays a crucial role in predicting the outcomes of chemical reactions involving Group 13 elements.