Problem 9 - Chemistry and Chemical Reactivity

Question

Americium, Am, is a radioactive element isolated from spent fuel in nuclear reactors and used in home smoke detectors. Depict its electron configuration using noble gas and spdf notations.

Step-by-Step Solution

Answer

Americium's electron configuration is \\( [Rn] \\\, 7s^2 \\\, 5f^7 \\\, 6d^1\\).

Step 1: Identify the Atomic Number

Americium (Am) is an element in the actinide series with an atomic number of 95. This means it has 95 electrons.

Step 2: Locate the Preceding Noble Gas

The noble gas preceding Americium is Radon (Rn), which has an atomic number of 86. This implies that the electron configuration of Americium can begin with the electron configuration of Radon.

Step 3: Add Electrons in the 7th Period

Continue the electron configuration from Radon's, which is \( [Rn] \, 7s^2\).

Step 4: Fill the 5f Subshell

The electrons continue to fill the 5f subshell. For Americium, this would involve placing 7 electrons in this subshell, giving \( 5f^7\).

Step 5: Add Electrons in the 6d Subshell

Americium does not fill the 6d subshell fully; it has one electron there, finalizing the configuration. So, we add \( 6d^1\) to the configuration.

Step 6: Finalize the Electron Configuration

Combine all the parts of the configuration to get the full electron configuration of Americium: \( [Rn] \, 7s^2 \, 5f^7 \, 6d^1\).

Key Concepts

Americium

Americium is a fascinating and vital element. It's part of the periodic table and carries the symbol Am with an atomic number of 95. This element is unique because it's radioactive and typically found in nuclear reactors. It's not an element you encounter every day, but it plays a crucial role in household devices like smoke detectors. Americium emits alpha particles, which help ionize air, allowing smoke detectors to sense smoke effectively. This element is a member of the actinide series, a group of elements known for their heavy, radioactive nature.

Noble Gas Notation

Noble gas notation is a simplified way of writing electron configurations. It helps avoid long and repetitive sequences by starting from the previous noble gas. For americium, we use radon (Rn), the noble gas before it, to simplify things. By using radon's electron configuration as a starting point,

• we can write: \( [Rn] \).
• This represents all the electrons up to the atomic number of radon, 86.

Then, add the electrons that fill the rest of americium's orbitals. This method makes learning electron configurations less cumbersome and more intuitive.

SPDF Notation

Understanding the SPDF notation is key to mastering electron configurations. This notation is based on the different atomic orbitals: s, p, d, and f. Each orbital

• has a specific shape and can hold a certain number of electrons.
• The s orbital can hold 2 electrons,
• p holds 6,
• d holds 10, and
• f holds 14.

For americium’s electron configuration, we add electrons beyond

• radon's 86 electrons starting with \( 7s^2 \), \( 5f^7 \), and \( 6d^1 \).

This notation helps provide a clear picture of where each electron is located.

Actinide Series

Americium belongs to the actinide series, a group of 15 elements from actinium to lawrencium. These elements are known for their

• heavy, radioactive characteristics.
• They contain f-orbitals, with electrons filling the 5f subshell.

This series:

• includes elements mostly used in advanced technology and energy applications.
• is part of the larger f-block in the periodic table.

Their unique electron configurations influence their chemical behavior and physical properties. Understanding this series helps in grasping important topics in chemistry, particularly in nuclear sciences.