CC4 The Periodic Table

• • The Periodic Table was first developed in 1869 by Dimitri Mendeleev.
• • Groups = columns (down)
  • Period= rows (across)
• • Metals on the left hand side of the periodic table.

  Non-metals on the right hand side.
• Similarities to Mendeleev’s periodic table and the one used now are:

  • Both put elements into groups and periods
  • Both put metals and non- metals separately
  • Both had elements with similar properties in the same group
• Differences are:

  • Mendeleev initially ordered the elements by increasing atomic mass not atomic number
  • Mendeleev left gaps for elements not yet discovered 
  • Mendeleev did not include the noble gases as they had not been discovered then.
• • Electrons are arranged in different shells around the nucleus. The way the electrons are arranged is called the electronic configuration.
• • The number of electrons in the outer shell is the same as the group number.
  • The number of  shells is the same as the period number.