Atomic Structure

The video explains the evolution of the periodic table, highlighting Mendeleev's initial arrangement by atomic mass and Mosley's later adjustment to order elements by atomic number. This change clarified the fixed nature of elements and their properties. The video also discusses electron shells and their role in defining periods and groups, explaining why elements in the same group have similar properties. The periodic table's structure is shown to reflect atomic structure and chemical behavior, validating Mendeleev's vision.

What does the arrangement of elements into vertical groups indicate about their properties?

Describe how Mendeleev's vision of the periodic table was validated.