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

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. (a) The heaviest alkaline earth metal

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Identify the heaviest alkaline earth metal by referring to the periodic table. Alkaline earth metals are found in Group 2, and the heaviest one based on atomic number is Radium (Ra).
Write the symbol for Radium, which is Ra.
Determine the electron configuration for Radium. Start by identifying the preceding noble gas to Ra, which is Radon (Rn), and use it as the core. Then, add the electrons in the outer shells beyond Radon.
The electron configuration of Radium, starting from Radon, involves filling the 7s orbital with two electrons. Thus, the configuration is represented as [Rn] 7s^2.
Draw the orbital-filling diagram for Radium. This involves a box diagram where the 7s orbital is represented with two arrows (one pointing up and one pointing down) indicating the two electrons in the 7s orbital.

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Key Concepts

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

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. The notation typically includes the energy level, subshell type, and the number of electrons in that subshell, often abbreviated using the nearest noble gas to simplify the representation of inner-shell electrons.
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Orbital-Filling Diagram

An orbital-filling diagram visually represents the arrangement of electrons in an atom's orbitals. Each box in the diagram corresponds to an orbital, and arrows indicate the presence of electrons, following Hund's rule and the Pauli exclusion principle. This diagram helps illustrate how electrons occupy orbitals and the overall electron configuration of an atom.
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Alkaline Earth Metals

Alkaline earth metals are the elements found in Group 2 of the periodic table, characterized by having two electrons in their outermost shell. These metals, including beryllium, magnesium, calcium, strontium, barium, and radium, are known for their reactivity, particularly with water, and their tendency to form +2 cations. The heaviest alkaline earth metal is radium, which is important for understanding its electron configuration and orbital filling.
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