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

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.