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Ch.5 - Periodicity & Electronic Structure of Atoms
Chapter 5, Problem 110c

Write the symbol, give the ground-state electron configuration, and draw an orbital-filling diagram for each of the following atoms. Use the abbreviation of the preceding noble gas to represent the inner-shell electrons. 
(c) The heaviest actinide metal

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Identify the heaviest actinide metal. The actinide series consists of elements with atomic numbers from 89 (Actinium) to 103 (Lawrencium). The heaviest actinide metal is Lawrencium (Lr).
Write the symbol for Lawrencium, which is Lr.
Determine the ground-state electron configuration for Lawrencium. Start by using the noble gas preceding Lawrencium in the periodic table, which is Rn (Radon), and then add the electrons in the order of their energy levels up to Lawrencium's atomic number (103).
Construct the electron configuration using the noble gas abbreviation: [Rn] 5f14 7s2 7p1. This configuration shows that after the Radon core, Lawrencium fills the 5f orbital completely, adds two electrons to the 7s orbital, and one electron to the 7p orbital.
Draw the orbital-filling diagram based on the electron configuration. Represent each orbital as a box and each electron as an arrow. Fill the 5f orbitals with 14 electrons (7 boxes, each with two arrows), the 7s orbital with 2 electrons (one box, two arrows), and the 7p orbital with 1 electron (one box, one arrow).

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Actinide Series

The actinide series consists of 15 elements from actinium (Ac, atomic number 89) to lawrencium (Lr, atomic number 103). These elements are characterized by the filling of the 5f orbitals and exhibit similar properties, including radioactivity and the ability to form complex compounds. Understanding the actinides is crucial for identifying the heaviest actinide metal, which is typically considered to be lawrencium.
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Electron Configuration

Electron configuration describes the distribution of electrons in an atom's orbitals. It is represented using a notation that indicates the energy levels and sublevels filled with electrons. For actinides, the electron configuration involves the 5f, 6d, and 7s orbitals, and it is essential to know how to write these configurations to accurately represent the ground state of the heaviest actinide metal.
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Orbital-Filling Diagram

An orbital-filling diagram visually represents the arrangement of electrons in an atom's orbitals. It uses boxes or lines to depict orbitals and arrows to indicate the electrons, following the Pauli exclusion principle and Hund's rule. Creating an orbital-filling diagram for the heaviest actinide metal helps illustrate how electrons occupy the available orbitals, providing insight into the atom's chemical behavior.
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