Question

Which of the following statements is falsc? (1) Thallium shows different oxidation states because of inert pair effect. (2) Stable compounds in \(+1\) oxidation state are formed by thallium. (3) Inert pair is a pair of outmost electrons which act as inert. (4) Among III A group elements, aluminium is present in cations only.

Short answer

Statement 4 is false.

Step-by-step solution

Understand Each Statement

Carefully read each of the statements to understand what they imply regarding the properties and behavior of thallium and aluminum, particularly with respect to oxidation states and electron behavior.

- Verify Statement 1

Statement 1: 'Thallium shows different oxidation states because of inert pair effect.' Thallium exhibits +1 and +3 oxidation states. The inert pair effect refers to the tendency of the s-electrons in the outermost electron shell to remain non-bonding or inert. This statement is correct.

- Verify Statement 2

Statement 2: 'Stable compounds in +1 oxidation state are formed by thallium.' Thallium is more stable in the +1 oxidation state due to the inert pair effect. This statement is correct.

- Verify Statement 3

Statement 3: 'Inert pair is a pair of outermost electrons that act as inert.' This describes the inert pair effect accurately, where the s-electrons of the outermost shell resist participating in bonding. This statement is correct.

- Verify Statement 4

Statement 4: 'Among III A group elements, aluminium is present only in cations.' While aluminum tends to form cations (Al³⁺), it can also form covalent bonds, such as in aluminum chloride (AlCl₃). This statement is incorrect as it overlooks aluminum's covalent bonding ability.

Conclusion - Identify the False Statement

Based on the analysis of each statement, conclude which statement does not hold true given the properties and behaviors of thallium and aluminum.

Key concepts

Oxidation States

Oxidation states are numerical values assigned to an element in a compound to indicate its degree of oxidation. The oxidation state of an element can vary depending on the chemical environment.
In the context of thallium, it exhibits two major oxidation states:

• +1 oxidation state: This is more stable for thallium due to the inert pair effect, where the s-electrons remain non-bonding.
• +3 oxidation state: Thallium can exhibit this state, although it is less stable compared to +1.

The inert pair effect significantly influences these oxidation states, making the +1 state particularly stable.
Other elements in the same group (III A) also show different oxidation states, but the stability can vary. For example:

• Boron typically shows a +3 oxidation state.
• Aluminum commonly forms compounds with a +3 oxidation state as well, but it can show covalent bonding traits in certain compounds like AlCl₃.
• Gallium and indium mainly exhibit +3, but can also show +1 oxidation states under specific conditions.

Understanding oxidation states helps predict the types of compounds an element can form and their chemical reactivity.

Thallium Chemistry

Thallium is a chemical element in group III A and is known for its unique chemical properties. It exists primarily in two oxidation states: +1 and +3.
The inert pair effect makes thallium more stable in the +1 oxidation state. The s-electrons (inert pair) in the outermost shell resist participating in bonding, leading to this stability.
Thallium compounds in the +1 state include:

• TlCl (thallium(I) chloride)
• Tl₂SO₄ (thallium(I) sulfate)

These compounds are generally more stable compared to those in the +3 state. In the +3 oxidation state, thallium can form compounds like Tl₂O₃ (thallium(III) oxide). However, these are less stable and tend to revert back to the +1 state.
Aside from the oxidation states, thallium's chemistry also involves:

• Toxicity: Thallium compounds are highly toxic and require careful handling.
• Uses: They are used in certain electronic devices and glass manufacturing.

Understanding thallium's chemistry is crucial in handling its compounds safely and utilizing its properties effectively.

Group III A Elements

Group III A elements, also known as group 13 elements, include boron (B), aluminum (Al), gallium (Ga), indium (In), and thallium (Tl). These elements share similar properties but also exhibit unique characteristics.
Some common features of Group III A elements include:

• **Valence Electrons:** They have three electrons in their outermost shell (valence electrons), leading to a +3 oxidation state in many compounds.
• **Metallic Character:** The metallic character increases down the group. For example, boron is a metalloid, while aluminum, gallium, indium, and thallium are metals.
• **Chemical Reactivity:** Reactivity also changes down the group. Aluminum is highly reactive, whereas thallium, being more inert due to the inert pair effect, is less so in its +1 oxidation state.

Boron: A metalloid, commonly found in borates and boric acid, used in glass and ceramics.
Aluminum: A lightweight metal, extensively used in construction, packaging, and aerospace industries.
Gallium: Used in semiconductors and LEDs.
Indium: Also used in electronics, particularly in LCD screens.
Thallium: Due to its toxicity, its use is limited but is used in some electronics and specialized glass manufacturing.
Understanding the group III A elements helps in grasping their diverse applications and the underlying trends in their chemical behavior.