The Development of the Periodic Table: From Dalton to Mendeleev

The video explores the historical development of the periodic table, highlighting contributions from scientists like John Dalton, Newlands, and Dmitri Mendeleev. Initially, elements were organized by atomic weights, leading to some misplacements. Mendeleev's innovative approach included leaving gaps for undiscovered elements and reordering elements based on chemical properties, which was later validated by the discovery of atomic numbers.

Before the discovery of atomic numbers, how were elements primarily organized?

• By atomic number

• By atomic mass

• By chemical properties

• By electron configuration

What was a major limitation of John Dalton's experiments?

• He used advanced equipment

• He accurately identified all elements

• He discovered the atomic nucleus

• He misidentified some compounds as elements

What was the main goal of John Newlands' Table of Octaves?

• To arrange elements by electron configuration

• To predict undiscovered elements

• To list elements by atomic number

• To group elements with similar chemical properties

Why were some elements misplaced in Newlands' table?

• Elements were arranged by atomic number

• Incomplete knowledge of existing elements

• Elements were grouped by electron configuration

• All elements were known at the time

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

• He grouped elements by electron configuration

• He left gaps for undiscovered elements

• He arranged elements by atomic number

• He ignored chemical properties

How did Mendeleev justify reversing the order of tellurium and iodine?

• By their electron configurations

• By their atomic numbers

• By their physical states

• By their atomic weights

What addition to the periodic table was made after the discovery of noble gases?

• Group 0

• Group 7

• Group 1

• Group 8