Mendeleev's periodic table

• What did Mendeleev create in 1869?

  He published his first periodic table of the elements.
• How did Mendeleev arrange the elements in his periodic table?

  He arranged them in order of increasing atomic weights.
• What did Mendeleev consider when organizing the elements?

  He took into account the properties of the elements and their compounds.
• What is the definition of relative atomic mass?

  It is the mean relative mass of the atoms of the different isotopes in an element.
• Why were early periodic tables considered incomplete?

  Many elements were unknown, and some were placed in incorrect groups.
• What significant prediction did Mendeleev make regarding undiscovered elements?

  He predicted the existence of 'eka-silicon'.
• What confirmed Mendeleev's periodic table after he predicted 'eka-silicon'?

  The discovery of germanium, which had similar properties to the predicted ones.
• Why did Mendeleev swap the positions of iodine and tellurium in his table?

  To align iodine with elements that had similar chemical properties.
• What is the atomic weight of iodine compared to tellurium?

  Iodine has a lower atomic weight than tellurium.
• What are the properties that Mendeleev considered when organizing elements?

  He considered both chemical and physical properties.
• What are the main features of Mendeleev's periodic table?

  • Arranged elements by increasing atomic weights
  • Left gaps for undiscovered elements
  • Grouped elements with similar chemical properties
• What were the limitations of early attempts to classify elements?

  • Incomplete due to unknown elements
  • Incorrect group placements for some elements
  • Based solely on atomic weights without considering properties