Question

Which electronic configuration represents a transition element? (1) \(1 \mathrm{~s}^{2} 2 \mathrm{~s}^{2} 2 \mathrm{p}^{6} 3 \mathrm{~s}^{2} 3 \mathrm{p}^{6} 3 \mathrm{~d}^{10} 4 \mathrm{~s}^{2} 4 \mathrm{p}^{6}\) (2) \(1 \mathrm{~s}^{2} 2 \mathrm{~s}^{2} 2 \mathrm{p}^{6} 3 \mathrm{~s}^{2} 3 \mathrm{p}^{6} 3 \mathrm{~d}^{10} 4 \mathrm{~s}^{2} 4 \mathrm{p}^{\prime}\) (3) \(1 \mathrm{~s}^{2} 2 \mathrm{~s}^{2} 2 \mathrm{p}^{6} 3 \mathrm{~s}^{2} 3 \mathrm{p}^{6} 3 \mathrm{~d}^{2} 4 \mathrm{~s}^{2}\) (4) \(1 \mathrm{~s}^{2} 2 \mathrm{~s}^{2} 2 \mathrm{p}^{6} 3 \mathrm{~s}^{2} 3 \mathrm{p}^{6} 4 \mathrm{~s}^{2}\)

Short answer

Option (3) represents a transition element.

Step-by-step solution

- Understanding Transition Elements

Transition elements have partially filled d-subshells. For an element to be a transition element, it should have a d-electron configuration in at least one of its common oxidation states.

- Analyzing the given configurations

We need to check each electronic configuration to see if it has a partially filled d-subshell. Let's analyze each option.

- Option (1)

The configuration is: \[1 \mathrm{~s}^{2} 2 \mathrm{~s}^{2} 2 \mathrm{p}^{6} 3 \mathrm{~s}^{2} 3 \mathrm{p}^{6} 3 \mathrm{~d}^{10} 4 \mathrm{~s}^{2} 4 \mathrm{p}^{6} \]The 3d subshell is completely filled with 10 electrons. This means it is not a transition element.

- Option (2)

The configuration is: \[1 \mathrm{~s}^{2} 2 \mathrm{~s}^{2} 2 \mathrm{p}^{6} 3 \mathrm{~s}^{2} 3 \mathrm{p}^{6} 3 \mathrm{~d}^{10} 4 \mathrm{~s}^{2} 4 \mathrm{p}^{'} \]There seems to be a misprint in the 4p subshell as 'p' without a superscript. This doesn't clarify the nature of the transition element correctly.

- Option (3)

The configuration is: \[1 \mathrm{~s}^{2} 2 \mathrm{~s}^{2} 2 \mathrm{p}^{6} 3 \mathrm{~s}^{2} 3 \mathrm{p}^{6} 3 \mathrm{~d}^{2} 4 \mathrm{~s}^{2} \]The 3d subshell is partially filled (with 2 electrons), which satisfies the requirement for a transition element.

- Option (4)

The configuration is: \[1 \mathrm{~s}^{2} 2 \mathrm{~s}^{2} 2 \mathrm{p}^{6} 3 \mathrm{~s}^{2} 3 \mathrm{p}^{6} 4 \mathrm{~s}^{2} \]There are no d-electrons present, so it is not a transition element.

- Conclusion

After analyzing each option, the only configuration that has a partially filled d-subshell is option (3), so it represents a transition element.

Key concepts

Electronic Configuration

The electronic configuration of an atom tells us the arrangement of electrons within its atomic orbitals. Understanding this is crucial because the behavior of elements, including their chemical reactivity and bonding tendencies, depends on their electronic configurations. In shorthand notation, electron configurations often start from the lowest energy level and fill up according to the Aufbau principle.
For example, the configuration ewline echoes when orbitals (like s, p, d, f) are filled. Transition elements typically have their electrons in and out of d-orbitals, making their configurations unique within the periodic table.

d-Subshell

The d-subshell is an atomic orbital type where electrons are located. It can hold a maximum of 10 electrons as it consists of 5 orbitals, each holding 2 electrons. Transition elements are characterized by having d-subshells that are not completely filled in one or more of their oxidation states.
When looking at the periodic table, the d-subshell starts getting filled during the 4th period and spans the 3rd to 12th groups, covering elements like Iron (Fe), Copper (Cu), and Zinc (Zn).

Oxidation States

Oxidation states refer to the degree of oxidation of an atom within a compound. Transition elements are notable for exhibiting multiple oxidation states due to the ability to lose different numbers of electrons from both s and d orbitals.
This variability in oxidation states is crucial for many chemical reactions and applications. For instance, Iron (Fe) can exhibit +2 and +3 oxidation states, making it versatile in forming various compounds.

Partially Filled d-Subshell

One of the distinctive features of transition elements is their partially filled d-subshells. Unlike other elements, which often have completely filled or completely empty d-orbitals, transition elements can have a range of configurations, such as d1, d2, up to d9.
This partially filled state allows them to participate in complex bonding and exhibit a range of oxidation states. For example, Titanium (Ti) has an electronic configuration of [Ar] 3d2 4s2 in its ground state, showcasing a partially filled d-subshell.

Periodic Table

The periodic table is an organized chart of elements, arranged by increasing atomic number, electron configurations, and recurring chemical properties. Transition elements are located in the central block of the periodic table (groups 3-12), between the s-block and p-block elements.
These elements are known for their metallic properties, such as high melting and boiling points, good conductivity, and the ability to form colored compounds. Their unique placement allows them to bridge and interact with elements on both sides of the table, contributing to their diverse chemistry.