Question

The increasing order of atomic radii of the following Group 13 elements is (A) \(\quad \mathrm{Al}<\mathrm{Ga}<\operatorname{In}<\mathrm{Tl}\) (B) \(\quad G a

Short answer

The increasing order of atomic radii for Group 13 is Al < Ga < In < Tl, so option (A) is correct.

Step-by-step solution

Understand Periodic Trends in Atomic Radius

Atomic radius generally increases as we move down a group in the periodic table. This is because new electron shells are being added, which are farther from the nucleus and thus the atom's size increases.

Apply Periodic Trend to Group 13 Elements

The order of elements in Group 13 from top to bottom is B, Al, Ga, In, Tl. Since Boron is not considered in the options given, we start with Aluminium. Following the trend, as we move down the group the atomic radius should increase: Al < Ga < In < Tl.

Choose the Correct Option

The correct option that follows the trend Al < Ga < In < Tl is (A).

Key concepts

Group 13 Elements

The Group 13 elements, also known as the boron group, play a significant role in fundamental chemistry concepts and real-world applications. This group contains the elements boron (B), aluminum (Al), gallium (Ga), indium (In), and thallium (Tl). Each element has its unique properties; however, they share certain similarities by being in the same group on the periodic table.

As students study these elements, particularly in JEE Advanced Chemistry, they encounter properties like electron configurations, reactivity, and atomic radii. It's crucial for students to understand that attributes like atomic radius have periodic trends which can be predictable as we go down the group. For instance, aluminum is well-known for its lightweight and strength, making it an ideal material in industries such as aerospace and packaging. Gallium is notable for its low melting point and is used in semiconductors, while indium is soft and malleable, finding its use in touchscreens and solders.

Their diverse applications make the study of Group 13 elements not just academically interesting, but also industrially relevant, encouraging learners to grasp both their chemical characteristics and practical uses.

Atomic Radius Increase

Understanding the concept of atomic radius and how it increases within a group is a cornerstone of chemistry education. The atomic radius is the distance from the nucleus to the outer boundary of the electron cloud. Why is this trend of increase significant in Group 13?

As we move down the group, the principal quantum number () of the outermost shell increases, indicating that the valence electrons are in a shell further away from the nucleus. This addition of a new electron shell, along with the increased distance of these outer electrons from the nucleus, results in an increase in atomic size. This concept is particularly emphasized in the context of JEE Advanced Chemistry, where students must understand trends in the periodic table to efficiently predict the properties of elements.

For example, when comparing gallium to its predecessor aluminum, gallium has an extra electron shell, leading to a larger atomic radius. One notable exception is the slight irregularity between gallium and aluminum, where gallium's radius is smaller than expected due to the higher effective nuclear charge experienced by its electrons.

JEE Advanced Chemistry

Candidates preparing for the JEE Advanced exam must have a thorough understanding of periodic trends, including atomic radius increases within a group. JEE Advanced Chemistry questions often assess a student's ability to apply these concepts to predict elemental behavior and characteristics.

The provided problem regarding the atomic radii of Group 13 elements is a classic example of questions that test knowledge on periodic trends. To approach such problems, candidates must use the step-by-step reasoning revolving around quantum numbers, effective nuclear charge, and the added energy levels as they appear in the periodic table. It is not just about memorizing facts; it requires a deep understanding of the underlying principles.

Mastering these concepts allows students to make educated guesses about unfamiliar elements and their potential reactions or uses. Additionally, this understanding is beneficial beyond examinations, as it lays the foundation for future studies in any chemistry-related field.