Multiple Choice
In atomic theory, all atoms of a given element have the same what?
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4. Atoms and Elements
Atomic Theory
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In atomic theory, what was Henry Moseley’s key contribution to organizing the periodic table?
A
He proposed that electrons orbit the nucleus in fixed energy levels to explain atomic line spectra.
B
He showed that elements should be arranged by increasing atomic number (based on nuclear charge) rather than by atomic mass.
C
He discovered the neutron and used it to explain isotopes and atomic mass differences.
D
He developed the first periodic table organized by recurring chemical properties and atomic mass.
Verified step by step guidance1
Understand the historical context of the periodic table before Moseley: it was primarily organized by atomic mass and recurring chemical properties, but some inconsistencies existed.
Recognize that Henry Moseley conducted experiments using X-ray spectra to study the atomic structure of elements, focusing on the concept of nuclear charge.
Learn that Moseley discovered a relationship between the frequency of X-rays emitted by elements and their nuclear charge, which corresponds to the number of protons in the nucleus.
From this, Moseley concluded that the correct way to organize the periodic table is by increasing atomic number (number of protons), not by atomic mass, resolving previous inconsistencies.
Therefore, Moseley’s key contribution was establishing the atomic number as the fundamental property for ordering elements in the periodic table, which improved its predictive power and accuracy.
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