Question

Identify two transition metal cations with each of the following electron configurations. (a) \([\mathrm{Ar}] 3 d^{6}\) (c) \([\mathrm{Ar}] 3 d^{5}\) (b) \(|\mathrm{Ar}| 3 d^{10}\) \((\mathrm{d})[\mathrm{Ar}] 3 d^{8}\)

Short answer

(a) Fe\(^{2+}\), Co\(^{3+}\); (b) Zn\(^{2+}\), Cu\(+\); (c) Mn\(^{2+}\), Fe\(^{3+}\); (d) Ni\(^{2+}\), Pd\(^{2+}\).

Step-by-step solution

Understanding Electron Configurations

Electron configurations indicate the distribution of electrons in an atom. Transition metals, when they form cations, lose electrons from the outermost shells, usually starting with the 4s orbital and then the 3d orbital.

Finding Transition Metals for [Ar] 3d^6

The electron configuration \([ ext{Ar}] 3d^6\) is characteristic of ions from the transition elements. Possible cations could be \( ext{Fe}^{2+} \) or \( ext{Co}^{3+} \). In their neutral state, they have the atomic numbers 26 and 27, respectively, and lose their s electrons when forming cations.

Finding Transition Metals for [Ar] 3d^5

The electron configuration \([ ext{Ar}] 3d^5\) corresponds to cation states like \( ext{Mn}^{2+} \) or \( ext{Fe}^{3+} \). Manganese has an atomic number of 25 and iron has 26.

Finding Transition Metals for [Ar] 3d^10

The \([ ext{Ar}] 3d^{10}\) configuration represents cations like \( ext{Zn}^{2+} \) or \( ext{Cu}^+ \). Zinc and copper, in their neutral form, have atomic numbers 30 and 29, respectively.

Finding Transition Metals for [Ar] 3d^8

The \([ ext{Ar}] 3d^8\) configuration can be seen in \( ext{Ni}^{2+} \) or \( ext{Pd}^{2+} \). Nickel and palladium have atomic numbers 28 and 46, respectively, and lose their electrons as specified to form these cations.

Key concepts

Electron Configurations

Electron configurations are a way of describing where electrons are located around the nucleus of an atom. They provide insight into how atoms will interact with each other to form chemical bonds.
Electrons fill orbitals in atoms in a specific fashion, starting from the lowest energy orbital to higher energy ones as per the Aufbau principle.

• For example, the electron configuration for a neutral iron atom is \([\text{Ar}]\,4s^2\,3d^6\), which means that it has completely filled the 1s, 2s, 2p, 3s, 3p orbitals along with a partly filled 4s and 3d orbitals.
• These configurations are crucial for predicting how an element will behave chemically.

When atoms form cations, as transition metals often do, they lose electrons. The initial electrons lost typically come from the outermost energy level, starting with the 4s before the 3d in transition metals. This loss changes the electron configuration.

Transition Metals

Transition metals are a group of metals found in the central block of the periodic table, specifically in groups 3 to 12. These metals are known for their ability to form different oxidation states and for their complex electron configurations.

• They have partially filled d orbitals, which are responsible for their characteristic properties like variable valency, formation of colored compounds, and magnetic properties.
• Their ability to lose different numbers of electrons gives rise to various cations, such as \(\text{Fe}^{2+}, \text{Fe}^{3+}\), or \(\text{Cu}^{+}, \text{Cu}^{2+}\).

This flexibility is due to the similar energy levels of the 4s and 3d sublevels, allowing these elements to participate in a broad range of chemical activities and be highly versatile in industrial applications.

Cation Formation

Cation formation involves an atom losing electrons to form a positively charged ion. This process is common in metals and particularly transition metals.

• In the case of transition metals, they often lose electrons from their outermost s orbital and sometimes from the d orbitals when forming cations.
• For instance, iron in its neutral state \(\text{Fe}\) becomes \(\text{Fe}^{2+}\) by losing two 4s electrons or \(\text{Fe}^{3+}\) by losing two 4s and one 3d electron.

The ability of transition metals to form multiple cations is crucial in fields such as catalysis and materials science, as these ions can engage in various chemical reactions. Understanding cation formation helps unravel the complexity of these substances.

Atomic Number

The atomic number is a fundamental property of an element that indicates the number of protons in its nucleus. This number defines the identity of the element and its position in the periodic table.

• For example, iron has an atomic number of 26, indicating it has 26 protons in its nucleus.
• The atomic number also determines the number of electrons in a neutral atom, which directly impacts its electron configuration.

This number is indispensable for predicting how the atom will arrange its electrons in its orbitals. It serves as the key to understanding the unique characteristics of each element, especially when considering electron distribution across different orbitals.

Electron Distribution

Electron distribution refers to how electrons are spread out in the different orbitals around an atom's nucleus. Accurate knowledge of electron distribution is critical to comprehending an element's chemical behavior.

• In transition metals, electrons are distributed across the s, p, and notably, the d orbitals.
• The distribution is not fixed and can change during chemical reactions. When forming cations, an element will typically redistribute its electrons, losing some from the outermost shell.

The peculiar distribution of electrons in transition metals allows these substances to have unique properties like high melting points, electrical conductivity, and formation of colored compounds. Understanding electron distribution helps predict how atoms will bond and what kinds of structures they will form.