Question

Write electron configurations for the common oxidation states of (a) silver. (b) gold.

Short answer

Ag+: [Kr] 4d^{10}; Au+: [Xe] 4f^{14} 5d^{10}; Au^{3+}: [Xe] 4f^{14} 5d^{8}.

Step-by-step solution

Determine the Ground State Electron Configuration

First, we need to write the electron configuration for the neutral atoms. Silver (Ag) has an atomic number of 47, so its ground state electron configuration is \[ \text{Ag}: [\text{Kr}]\,4d^{10}5s^1 \]. Gold (Au), with an atomic number of 79, has a ground state electron configuration of \[ \text{Au}: [\text{Xe}]\,4f^{14}5d^{10}6s^1 \].

Identify the Common Oxidation States

Silver commonly exhibits a +1 oxidation state, and gold commonly exhibits both +1 and +3 oxidation states. Thus, we need to consider how these oxidation states are formed from the ground state.

Electron Configuration for Ag+ (Silver's +1 Oxidation State)

When silver loses one electron to form a +1 oxidation state, it loses the single 5s electron. Therefore, the electron configuration for \( \text{Ag}^+ \) is \[ [\text{Kr}]\,4d^{10} \].

Electron Configuration for Au+ (Gold's +1 Oxidation State)

In the +1 oxidation state, gold loses the 6s electron. The electron configuration for \( \text{Au}^+ \) becomes \[ [\text{Xe}]\,4f^{14}5d^{10} \].

Electron Configuration for Au3+ (Gold's +3 Oxidation State)

In the +3 oxidation state, gold loses the 6s electron and two 5d electrons. The configuration for \( \text{Au}^{3+} \) is \[ [\text{Xe}]\,4f^{14}5d^{8} \].

Key concepts

Oxidation States

An oxidation state is a key concept in understanding how atoms interact in chemical reactions. It represents the degree of oxidation—the loss of electrons—of an atom in a compound. Essentially, an atom's oxidation state is an indicator of its ability to donate or accept electrons. Understanding oxidation states helps us determine the nature of the chemical bonding and reactivity of a substance.

When we talk about oxidation states in terms of electron configuration, we focus on the electrons that are lost or gained by an atom during a chemical reaction. For instance:

• Silver typically has a +1 oxidation state, meaning it loses one electron, usually from the outermost s orbital.
• Gold can exist in +1 and +3 oxidation states, losing either one s electron or an s and two d electrons.

The loss of an electron to form ions influences the chemical bonding properties of these metals, changing how they interact with other elements.

Transition Metals

Transition metals are a group of elements found in the center of the periodic table, encompassing groups 3 through 12. They are unique due to their ability to form compounds with variable oxidation states, which affects their behavior in reactions and the types of bonds they form.

These metals are characterized by partially filled d orbitals, which contribute to several distinctive properties:

• They often exhibit multiple oxidation states. For example, silver and gold, as transition metals, have different common oxidation states.
• They can form colored compounds due to d-d electron transitions.
• They are generally good conductors of heat and electricity.

The ability to exhibit various oxidation states shows the chemical versatility of transition metals, allowing them to participate in a wide variety of chemical reactions.

Chemical Bonding

Chemical bonding involves the attraction between atoms that allows the formation of chemical substances containing two or more atoms. The type of bond formed can determine the properties of a substance, including its reactivity, solubility, and hardness.

Transition metals like silver and gold engage in metallic bonding but can also participate in other forms of bonding, influenced by their oxidation states. The oxidation state determines the number of electrons available for bonding:

• In a +1 oxidation state, there is typically one less electron available for forming bonds.
• In a +3 oxidation state, there are even fewer electrons available, often altering the metal's typical bonding properties.

Understanding the electron configuration of these elements in various oxidation states helps us predict and explain their bonding behavior. These insights reveal why certain compounds form and how they can be manipulated for various industrial applications.