Mendeleev's periodic table

• Who made an early periodic table?

  Dmitri Mendeleev
• How are elements arranged in the modern periodic table?

  Elements are arranged in order of atomic number in periods and groups
• What does the electronic structure model represent?

  It models how electrons are arranged in atoms
• What were early attempts to classify elements based on?

  • Arranging elements in order of atomic weights
  • Atomic weight is equivalent to relative atomic mass
  • Early tables were incomplete and had misclassified elements
• What is a substance made of one type of atom called?

  An element
• 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?

  Because many elements were unknown and some were misclassified
• Who was Dmitri Mendeleev?

  A Russian chemist who published the first periodic table in 1869
• How did Mendeleev arrange the elements in his periodic table?

  In order of increasing atomic weights and by their properties
• What was the significance of the gaps Mendeleev left in his periodic table?

  They allowed him to predict the properties of undiscovered elements
• What element did Mendeleev predict that was later discovered?

  Germanium
• 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 relationship between iodine and tellurium in Mendeleev's periodic table?

  Iodine has a lower atomic weight than tellurium but was placed after it
• What are the properties considered by Mendeleev when creating his periodic table?

  • Chemical properties (reactions substances can take part in)
  • Physical properties (color, boiling point)
  • Arrangement based on atomic weights
• What are the limitations of early periodic tables?

  • Incomplete due to unknown elements
  • Misclassification of elements
  • Lack of understanding of atomic structure