Attempts of elements classification: The Development of the Periodic Table

The video tutorial discusses the history of element discovery, starting with gold, silver, copper, and iron. By 1800, 30 elements were known, and over the next century, more than 60 were identified. Scientists sought patterns among these elements, leading to Dmitry Mendeleev's creation of the periodic table in 1869. Mendeleev arranged elements by atomic mass and identified gaps, predicting the existence of undiscovered elements. His predictions were later confirmed as new elements were found.

Which metals were known to be forged in ancient times?

• Aluminum, zinc, lead, and tin

• Gold, silver, copper, and iron

• Mercury, bismuth, antimony, and arsenic

• Platinum, palladium, nickel, and cobalt

By the year 1800, how many elements had been identified?

• 70

• 10

• 30

• 50

Who published the table of elements in 1869 that led to the modern periodic table?

• Antoine Lavoisier

• Dmitry Mendeleev

• John Dalton

• Henry Moseley

On what basis did Mendeleev arrange the elements in his table?

• Electronegativity

• Chemical reactivity

• Atomic mass

• Atomic number

What did Mendeleev predict about the gaps in his periodic table?

• They indicated the end of the periodic table

• They were errors in his calculations

• They represented elements that were yet to be discovered

• They were placeholders for isotopes