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Ch.5 - Periodicity & Electronic Structure of Atoms
Chapter 5, Problem 117

What is the atomic number and expected ground-state electron configuration of the yet undiscovered element directly below Fr in the periodic table?

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Key Concepts

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

Atomic Number

The atomic number of an element is defined as the number of protons found in the nucleus of its atoms. It determines the element's identity and its position in the periodic table. For example, francium (Fr) has an atomic number of 87, meaning it has 87 protons. The element directly below francium would have an atomic number of 88.
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Electron Configuration

Electron configuration describes the distribution of electrons in an atom's orbitals. It follows the Aufbau principle, which states that electrons fill the lowest energy orbitals first. For the element below francium, which is expected to be radium (Ra), the ground-state electron configuration would be [Rn] 7s², indicating that it has two electrons in the outermost s orbital.
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Periodic Table Trends

The periodic table exhibits trends in atomic properties, including atomic size, ionization energy, and electron affinity. Elements in the same group, like francium and the undiscovered element below it, share similar chemical properties and electron configurations. Understanding these trends helps predict the behavior of elements based on their position in the periodic table.
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