Question

Write electron configurations for each transition metal. (a) \(\mathrm{Mn}\) (b) \(\mathrm{Ti}\) (c) \(\mathrm{Cd}\) (d) \(\mathrm{V}\)

Short answer

The electron configurations are (a) Mn: [Ar] 4s2 3d5, (b) Ti: [Ar] 4s2 3d2, (c) Cd: [Kr] 5s2 4d10, (d) V: [Ar] 4s2 3d3.

Step-by-step solution

Identifying Atomic Numbers

Find the atomic numbers of the transition metals Mn, Ti, Cd, and V from the periodic table. Mn has atomic number 25, Ti has atomic number 22, Cd has atomic number 48, and V has atomic number 23.

Determining Electron Configurations

Write down the electron configurations based on the atomic numbers. Electrons fill atomic orbitals in the order of increasing energy levels following the 'Aufbau principle'. Use the order: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, and so on.

Writing Electron Configurations for Mn

For Mn (atomic number 25), the electron configuration is 1s2 2s2 2p6 3s2 3p6 4s2 3d5.

Writing Electron Configurations for Ti

For Ti (atomic number 22), the electron configuration is 1s2 2s2 2p6 3s2 3p6 4s2 3d2.

Writing Electron Configurations for Cd

For Cd (atomic number 48), the electron configuration is 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10.

Writing Electron Configurations for V

For V (atomic number 23), the electron configuration is 1s2 2s2 2p6 3s2 3p6 4s2 3d3.

Key concepts

Transition Metals

Transition metals are elements located in the d-block of the periodic table, which includes groups 3 through 12.
They are known for their ability to exhibit multiple oxidation states and to form colorful compounds.

Unlike s-block elements, transition metals have a unique electron filling order due to the energy levels of their orbitals. For example, manganese (Mn) has an electron configuration stretching into the 3d sublevel, which is characteristic of transition metals. In many cases, the distinguishing feature of these elements is their partially filled d orbitals, which account for their complex chemistry and magnetic properties.

Transition metals like titanium (Ti), often play vital roles in industrial catalysis and materials science because of their diverse chemical reactivity and ability to form various alloys.

Aufbau Principle

The Aufbau Principle is a fundamental guideline for predicting the electron configurations of atoms.
Stemming from German, meaning 'building up', this principle states that electrons are added to atomic orbitals starting from the lowest energy level and moving to higher ones systematically.

The correct electron configuration for a given element can be determined by following a specific order: 1s, 2s, 2p, 3s, 3p, 4s, 3d, etc. For instance, when configuring titanium (Ti), electrons occupy the 3d orbital after the 4s, despite the 3d being at a higher principal quantum number.

It is critical to note exceptions to the Aufbau Principle within the d-block elements. Some transition metals have configurations that are slightly adjusted to achieve a more stable and lower energy arrangement, often leading to half-filled or completely filled d subshells.

Atomic Orbitals

Atomic orbitals are regions in space around the nucleus of an atom where there is a high probability of locating electrons.
Each orbital can hold a maximum of two electrons, with sublevels designated s, p, d, and f, each with a distinct shape and energy level.

The s orbitals are spherical, p orbitals are dumbbell-shaped, d orbitals are clover-shaped, with f orbitals being even more complex. The electron configurations for transition metals like cadmium (Cd) display how these orbitals are filled in accordance with the Aufbau Principle and Hund's Rule, which dictates that electrons will fill an unoccupied orbital before they pair up.

The complexity of electron configurations, especially within transition metals, arises partly because d and f orbitals have similar energy levels making their filling sequence less intuitive than s and p orbitals.

Periodic Table

The periodic table is a systematic arrangement of the chemical elements, ordered by their atomic number, electron configuration, and recurring chemical properties.
Its structure allows us to predict an element's behavior and properties. For example, vanadium (V) falls into the transition metals category and its properties can be inferred based upon its position on the table.

Each row on the periodic table is called a period, which indicates the number of electron shells an atom has. Each column is termed a group and denotes elements with similar chemical behaviors. The placement of an element in the d-block signifies that its electron configuration will involve d orbitals, which is crucial for outlining the electron distributions of transition metals like those discussed in the electron configuration exercise.

Understanding the layout of the periodic table is essential for mastering the electron configurations of elements and predicting their chemical interactions.