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    In which order did Mendeleev arrange the elements in his periodic table?
    Question

    In which order did Mendeleev arrange the elements in his periodic table?

    A.

    Decreasing atomic radius

    B.

    Increasing number of neutrons

    C.

    Increasing atomic number

    D.

    Increasing atomic mass

    Correct option is D

    The correct answer is (D) Increasing atomic mass

    Explanation:

    • Mendeleev arranged the elements in his periodic table primarily by increasing atomic mass.

    • He noticed that when elements were arranged in this way, their properties showed a periodic pattern, leading to the formation of groups with similar characteristics.

    • While Mendeleev’s periodic law is based on atomic mass, he also left gaps for undiscovered elements and even predicted their properties based on the patterns observed.

    • It was only later that atomic number was established as the correct criterion for arranging elements in the modern periodic table, as proposed by Moseley.

    Information Booster:

    • Mendeleev's Periodic Table: Mendeleev published his periodic table in 1869, organizing elements by their atomic masses and properties.

    • Periodic Law: Mendeleev's Periodic Law states that the properties of elements are a periodic function of their atomic masses, which was later refined by Moseley’s law based on atomic numbers.

    • Prediction of Elements: Mendeleev predicted the existence and properties of undiscovered elements like gallium, scandium, and germanium, which were later discovered and validated his table.

    • Periodic Trends: Mendeleev noticed that elements with similar properties occurred at regular intervals when arranged by atomic mass.

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