Multiple Choice
In atomic theory, who is most commonly credited with developing the electron cloud (quantum mechanical) model of the atom?
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4. Atoms and Elements
Atomic Theory
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In Mendeleev's first widely accepted periodic table, how were the elements primarily arranged?
A
Alphabetically by element name, grouping elements with similar chemical properties
B
By increasing number of neutrons, grouping elements with similar chemical properties
C
By increasing atomic number, grouping elements with similar chemical properties
D
By increasing atomic mass, grouping elements with similar chemical properties
Verified step by step guidance1
Understand the historical context: Dmitri Mendeleev created the first widely accepted periodic table in the 19th century to organize elements based on their properties.
Recall that Mendeleev arranged elements primarily by increasing atomic mass, not atomic number or number of neutrons, because the concept of atomic number was not yet established.
Recognize that Mendeleev grouped elements with similar chemical properties into columns (groups or families) to highlight periodic trends.
Note that arranging by atomic mass allowed Mendeleev to predict the existence and properties of undiscovered elements by leaving gaps in his table.
Summarize that Mendeleev's periodic table was organized by increasing atomic mass while grouping elements with similar chemical properties together.
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