Question

In which period and group does an electron first appear in a \(d\) orbital?

Short answer

An electron first appears in a d orbital in the fourth period, group 3, with the element scandium.

Step-by-step solution

Understanding the Periodic Table Structure

The periodic table is organized into periods (horizontal rows) and groups (vertical columns). The period number indicates the highest energy level that an electron occupies for an atom in that row. Groups organize elements by their valence electron configurations.

Identifying the Transition Metals

Electrons occupy the d orbitals starting in the transition metals, which are found in groups 3 through 12 on the periodic table. These elements have electrons entering the penultimate energy level, specifically in the d subshell.

Determining the First Appearance of a d Orbital

The first appearance of an electron in a d orbital occurs in the fourth period, group 3, with the element scandium (Sc). This is because Scandium has the electronic configuration [Ar]3d1 4s2, indicating that one electron is in the 3d orbital.

Key concepts

Periodic Table Structure

The periodic table is akin to a cosmic address book, charting elements based on their atomic structure and electron configuration. Think of it as your ultimate map to understanding how elements relate to each other.

It consists of seven horizontal rows known as periods and 18 vertical columns called groups or families. The periods correlate with the highest occupied energy level of the atoms, while the groups are organized by common properties and configurations of valence electrons, which are the electrons available for bonding in the outermost shell.

Transition Metals

Delving into the heart of the periodic table, we encounter the transition metals, ranging from group 3 to group 12. These metals are the master alchemists of the elements – forging colorful compounds, possessing varying oxidation states, and featuring in a myriad of applications from industrial catalysts to biological processes.

What sets them apart is their penultimate energy level, which starts filling up with electrons in the so-called d orbitals. These orbitals are roomier abodes for electrons, shaping the unique properties of transition metals including their remarkable ability to conduct electricity and heat.

Valence Electron Configurations

Valence electrons are the social butterflies of an atom – they're the ones that interact and bond, holding the material world together. Their configuration refers to the arrangement of electrons in the atom's most external shell, dictating the chemical behavior of the element.

The precise patterning of valence electrons is pivotal for bonding, as it determines how an element will interact with others. Transition metals have particularly interesting valence setups due to their d orbitals, allowing them to form an assortment of bonds ranging from iconic to covalent, single to multiple.

Electron Configuration of Scandium

Scandium, the gateway to the d orbital club, carries an electronic configuration of [Ar]3d1 4s2. This signifies that it has 21 electrons with one shy electron starting a new journey in the 3d orbital aside its 18 companions filling the Argon core, and two electrons holding the fort in the 4s orbital.

When examining scandium on the periodic table, we find it perched in the fourth period, signifying that its electrons have ventured into the fourth energy level. And in group 3, it stands as the first element in this group to have an electron occupy the d orbital. It's an exciting moment in the atomic world – the point at which properties transition and the rich chemistry of the d block begins.