Why Is The Periodic Table Arranged The Way It Is?

In the 1860s, Dmitri Mendeleev, a lecturer at Saint Petersburg University, faced the challenge of organizing elements and creating an authoritative chemistry textbook. Despite limited knowledge of elements and incorrect data, he succeeded in writing 'Principles of Chemistry' and developed the periodic table. Mendeleev arranged elements by atomic weight and valence, predicting properties of undiscovered elements. The periodic table provides insights into atomic numbers, symbols, and weights, and organizes elements into periods and groups based on electron shells. Mendeleev's work laid the foundation for modern chemistry, offering a roadmap for known and unknown elements.

What was one of Mendeleev's key methods in organizing the periodic table?

• Listing elements by their discovery date

• Grouping elements by color

• Arranging elements by atomic weight and valence

• Arranging elements alphabetically

What does the atomic number of an element represent?

• The number of electron shells

• The number of neutrons in the nucleus

• The element's position in the periodic table

• The number of protons in the nucleus

How is the atomic symbol useful in chemistry?

• It indicates the element's atomic weight

• It provides the element's discovery year

• It helps in writing chemical equations faster

• It shows the element's color

What do all elements in the same period of the periodic table have in common?

• They have the same number of electron shells

• They have the same number of protons

• They have the same atomic number

• They have the same atomic weight

What is a characteristic of elements in the same group of the periodic table?

• They are all metals

• They have the same atomic weight

• They have similar outer electron configurations

• They have the same atomic number