Textbook Question
Use the periodic table to determine each quantity. a. the number of 2s electrons in Li
Ch.9 - Periodic Properties of the Elements
Chapter 9, Problem 46
Use the periodic table to determine each quantity.
b. the number of 3d electrons in Cr
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Identify the electron configuration of chromium (Cr) using the periodic table.
Recall that chromium is an exception to the typical electron configuration rules.
Write the electron configuration for Cr: \([\text{Ar}] 3d^5 4s^1\).
Determine the number of electrons in the 3d subshell from the electron configuration.
Conclude that the number of 3d electrons in Cr is the number of electrons in the 3d subshell.
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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. For transition metals like chromium (Cr), the electron configuration is crucial for understanding how many electrons occupy specific subshells, such as the 3d subshell. Chromium has an atomic number of 24, and its electron configuration is [Ar] 3d5 4s1, indicating it has five electrons in the 3d subshell.
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Transition Metals
Transition metals are elements found in the d-block of the periodic table, characterized by their ability to form variable oxidation states and colored compounds. They typically have partially filled d orbitals, which play a significant role in their chemical properties and bonding behavior. Understanding the unique characteristics of transition metals is essential for determining electron counts in specific subshells.
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Periodic Table Trends
The periodic table organizes elements based on their atomic number and electron configurations, revealing trends in properties such as electronegativity, ionization energy, and atomic size. These trends help predict the behavior of elements, including how many electrons occupy certain orbitals. For chromium, recognizing its position in the periodic table aids in understanding its electron configuration and the number of 3d electrons.
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Related Practice
Textbook Question
Use the periodic table to write an electron configuration for each element. Represent core electrons with the symbol of the previous noble gas in brackets. a. P b. Ge c. I
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Textbook Question
Use the periodic table to determine each quantity. c. the number of 4p electrons in Br
Textbook Question
Name an element in the fourth period (row) of the periodic table with the following: a. five valence electrons
Textbook Question
Name an element in the fourth period (row) of the periodic table with the following: b. four 4p electrons
Textbook Question
Name an element in the fourth period (row) of the periodic table with the following: c. three 3d electrons