The periodic table

• Who created the periodic table?

  Dmitri Mendeleev - 1869.
• How did Dmitri Mendeleev arrange the periodic table?

  He began sorting out elements into groups based on their general properties (and their compounds). He could put elements with similar properties in groups.
• How was Mendeleev able to predict undiscovered elements?

  He left gaps in the periodic table to keep the elements arranged in similar properties. This allowed certain elements to be predicted like germanium.
• Mendeleev thought he had arranged elements in order of increasing relative atomic mass but this was not always true because of the relative abundance of isotopes of some pairs of elements in the periodic table.
• What is the atomic number of an element?

  The atomic number of an element is the number of protons in the nucleus of an atom. (The lower number).
• How is the periodic table arranged?

  • Elements are arranged by increasing atomic number in periods.
  • Elements with similar properties are grouped in vertical columns called groups.
• Where are the metals and non-metals found in the periodic table?

  Metals are found on the left side of the periodic table, while non-metals are found on the right side.

  
• The electronic configuration of an element is related to its position in the periodic table.