Question

Predict electron configurations for the following elements of the actinide series of elements. Use noble gas and spdf notations. (a) Plutonium, Pu. The element is best known as a by-product of nuclear power plant operations. (b) Curium, Cm. This actinide was named for Marie Curie (page 72 ).

Short answer

Plutonium: [Rn] 5f^6 7s^2; Curium: [Rn] 5f^7 6d^1 7s^2.

Step-by-step solution

Understand the Exercise

The task requires identifying the electron configurations for the elements Plutonium (Pu) and Curium (Cm) using noble gas and spdf notation, particularly focusing on their place in the actinide series.

Review Electron Configuration Concepts

Learn that noble gas notation involves using the electron configuration of the closest noble gas before the element and then continuing with the configuration from there. Actinides start filling the 5f subshell, typical for elements in this series.

Identify the Closest Noble Gas

For both Pu and Cm, the closest noble gas is Radon (Rn), which has the electron configuration \([Xe]6s^24f^{14}5d^{10}6p^6\). This forms the basis for writing noble gas notation.

Configure Plutonium (Pu)

Plutonium (Pu) has an atomic number of 94. Its electron configuration starts from Radon: \([Rn]\ 5f^6\ 7s^2\), continuing to fill the 5f subshell after completing the configuration for Radon.

Configure Curium (Cm)

Curium (Cm) has an atomic number of 96. Its electron configuration starts from Radon: \([Rn]\ 5f^7\ 6d^1\ 7s^2\). Note it continues after Plutonium by filling the 5f and then beginning the 6d subshell.

Key concepts

Actinide Series

The actinide series consists of 15 chemical elements with atomic numbers from 89 to 103, spanning from actinium to lawrencium. These elements are known for having their 5f subshell gradually filled with electrons. This electron arrangement gives the actinides their unique chemical and physical properties. They are all radioactive and many of them are man-made. The actinide elements are often found in nuclear reactors due to their ability to absorb neutrons. Important points about the actinide series:

• Actinides are located in the f-block of the periodic table.
• They exhibit complex electron configurations due to the filling of the 5f subshell.
• Examples include naturally occurring Thorium and Uranium, and synthetic elements like Plutonium and Curium.

Noble Gas Notation

Noble gas notation is a shorthand electron configuration that begins with the electron configuration of the last noble gas before the element in question. This notation simplifies understanding by reducing the length and complexity of electron configurations. The noble gas used acts as a reference point. Characteristics of noble gas notation include:

• Reduction in the length of the electron configuration.
• Facilitates easier comparisons between elements in the same group or period.
• Example: Plutonium (Pu) configuration begins with [Rn] because Radon is the closest noble gas.

spdf Notation

The spdf notation is a way of expressing the electron configuration of an atom. It stands for the shapes of atomic orbitals, which include s (sharp), p (principal), d (diffuse), and f (fundamental). Key characteristics of spdf notation:

• Utilizes the principal quantum number and the subshell letter.
• Indicates the number of electrons in each subshell with a superscript.
• Example: For Plutonium, the notation is [Rn] 5f⁶ 7s² where electrons fill the 5f and 7s subshells.

This notation helps comprehensively describe the electronic structure of an atom and is widely used to discuss chemical behavior.

Plutonium

Plutonium, symbol Pu and atomic number 94, is a radioactive actinide metal. It is known for its significant role in nuclear power and weaponry. Understanding its electron configuration is critical in nuclear chemistry since it influences its behavior in nuclear reactions. For Plutonium:

• The electron configuration begins with Radon (Rn), resulting in [Rn] 5f⁶ 7s².
• This configuration is an example of the filling of the 5f subshell found in actinides.
• Pu is produced in nuclear reactors as a by-product.
able comprehensive

Curium

Curium, symbol Cm and atomic number 96, is another radioactive actinide, named after Marie Curie. It also plays a role in scientific research mostly due to its radioactive properties, making it valuable for space missions in power generation. Curium's electron configuration consists of:

• Starting from Radon, it is [Rn] 5f⁷ 6d¹ 7s².
• It shows further filling of the 5f subshell after Plutonium, with the beginning of the 6d subshell.
• Its position in the actinide series allows it to provide insight into the f-element chemistry.