Electron Configurations of Transition Metals: Videos & Practice Problems

Transition metals are found in the d block of the periodic table and lose electrons from the highest principal quantum number (n) first when forming cations. For example, titanium (atomic number 22) has the condensed electron configuration of argon 4s²3d². When titanium forms a 3+ cation, it loses two electrons from the 4s orbital and one from the 3d orbital, resulting in the configuration argon 3d¹. Understanding electron configurations is crucial for predicting the behavior of transition metals in chemical reactions.

Transition Metals

Transition metals are found in the d block of the periodic table, also known as the group B elements. When forming cations, electrons are lost starting from the highest principal quantum number (n). For example, titanium, which has an atomic number of 22, has 22 electrons when neutral. The last noble gas preceding titanium is argon, allowing us to write its condensed electron configuration as follows: starting with argon, we add the electrons in the 4s and 3d orbitals.

The configuration begins with argon, followed by filling the 4s orbital with two electrons (4s²) and then the 3d orbital with two electrons (3d²). According to the Pauli exclusion principle, these two electrons in the 4s orbital must have opposite spins. Additionally, Hund's rule states that electrons in degenerate orbitals (orbitals of the same energy) are filled singly before pairing occurs. Thus, the complete condensed electron configuration for titanium is:

Ti: [Ar] 4s² 3d²

When titanium forms a cation with a +3 charge (Ti³⁺), it loses three electrons. The first two electrons are removed from the 4s orbital, which corresponds to n=4, leaving it empty. The third electron is then removed from the 3d orbital, resulting in one electron remaining in the 3d orbital. Therefore, the condensed electron configuration for titanium in the +3 oxidation state can be expressed as:

Ti³⁺: [Ar] 3d¹

In summary, when writing the condensed electron configuration for transition metals and their cations, always start with the nearest noble gas and account for the loss of electrons from the highest energy orbitals first.

Electron Configurations Of Transition Metals Example

The electron configuration for a neutral vanadium atom is represented as [Ar] 4s2 3d3, where [Ar] denotes the electron configuration of argon, the preceding noble gas. When forming the vanadium 3 ion (V³⁺), three electrons are removed from the neutral atom.

To determine which electrons are lost, we follow the principle that electrons are removed from the highest energy level first. In this case, the two electrons from the 4s orbital are removed first, followed by one electron from the 3d orbital. After these removals, the resulting electron configuration for the vanadium 3 ion is [Ar] 3d2.

This condensed electron configuration indicates that the vanadium 3 ion has two electrons in the 3d subshell, reflecting its oxidation state and stability in various chemical environments.

Write an electron configuration for ion of Tungsten (IV).

• A. [Xe]6s²4f¹⁴5d⁴
• B. [Xe]6s²4f¹⁴
• C. [Xe]6s²4f¹⁴5d⁸
• D. [Xe]4f¹⁴5d²

Answer: (D)

Determine electron configuration for the ion of Cd in cadmium sulfide (CdS) compound.

• A. [Kr]5s²4d¹⁰
• B. [Kr]4d¹⁰
• C. [Kr]5s²4d⁸
• D. [Kr]5s²4d¹⁰5p²

Answer: (B)

Here’s what students ask on this topic:

What is the electron configuration of a neutral titanium (Ti) atom?

The electron configuration of a neutral titanium (Ti) atom, which has an atomic number of 22, starts from the last noble gas argon (Ar). The configuration is then followed by filling the 4s orbital with 2 electrons and the 3d orbital with 2 electrons. Therefore, the condensed electron configuration of a neutral titanium atom is [Ar] 4s² 3d².

How do you determine the electron configuration of a transition metal cation?

To determine the electron configuration of a transition metal cation, you first write the electron configuration of the neutral atom. Then, remove electrons starting from the orbital with the highest principal quantum number (n). For example, for Ti³⁺, you start with the neutral configuration [Ar] 4s² 3d². Since Ti³⁺ has lost 3 electrons, you remove 2 electrons from the 4s orbital and 1 electron from the 3d orbital, resulting in the configuration [Ar] 3d¹.

Why are electrons removed from the 4s orbital before the 3d orbital in transition metals?

Electrons are removed from the 4s orbital before the 3d orbital in transition metals because the 4s orbital has a higher principal quantum number (n=4) compared to the 3d orbital (n=3). When forming cations, electrons are lost from the highest energy level first, which corresponds to the highest principal quantum number. Therefore, electrons are removed from the 4s orbital before the 3d orbital.

What is Hund's rule and how does it apply to electron configurations?

Hund's rule states that electrons will fill degenerate orbitals (orbitals with the same energy) singly first, with parallel spins, to maximize the number of unpaired electrons. This rule helps to minimize electron-electron repulsions within an atom. For example, in the 3d orbitals of titanium, the two electrons will occupy separate orbitals with parallel spins before pairing up in the same orbital. This results in the configuration [Ar] 4s² 3d² for neutral titanium.

What is the Pauli Exclusion Principle and how does it affect electron configurations?

The Pauli Exclusion Principle states that no two electrons in an atom can have the same set of four quantum numbers. This means that an orbital can hold a maximum of two electrons, and they must have opposite spins. In electron configurations, this principle ensures that electrons are distributed among orbitals in a way that each electron has a unique set of quantum numbers, leading to specific arrangements such as [Ar] 4s² 3d² for neutral titanium.