The Development of the Periodic Table

• These are elements that are grouped into sets of three.

  Law of Triads
• Who introduced the law of triads?

  Dobereiner
• Elements arranged in order of increasing atomic mass. Every eighth element seemed to share similar properties with the first.

  Law of Octaves
• Who introduced the law of Octaves?

  John Newlands
• He arranged elements by increasing atomic mass. Unlike others, he left gaps for elements not yet discovered. In 1871 he revised his periodic table.

  Dmitri Mendeleev
• He arranged the elements by their atomic number through his experiments with X-rays. It also laid the foundation for the modern periodic table we use today.

  Henry Moseley
• He discovered the transuranium elements. He arranged the periodic table by placing the actinide series below the lanthanides.

  Glenn Seaborg
• Who proposed the law of traids?

  Johann Dobereiner
• What is a triad according to Dobereiner?

  Three elements with similar properties
• According to the Law of Octaves, similar properties repeat every how many elements?

  8
• Who is known as the father of the periodic table?

  Dmitri Mendeleev
• What did Mendeleev use to arrange elements in his periodic table?

  Atomic Mass
• What was special about Mendeleev's periodic table?

  He predicted missing elements
• Who revised the periodic law and arranged elements by atomic number?

  Henry Moseley
• Show the Sequence of Developments in the Periodic Table.

  Law of Triads -> Law of Octaves -> Periodic Law -> Revised Periodic Law