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The Periodic Table

Science — First Preparatory

The Periodic Table

Order of the elements and layout of the table

Order of the elements and layout of the table

  • In the modern periodic table the elements are arranged in increasing order of their atomic number, which is the number of protons in the nucleus of each atom.
  • The table has 7 periods (horizontal rows) and 18 groups (vertical columns).
Comparison aspectMain ideaKeywords
Period (row)the number of energy levels occupied by electrons in the atom. An element in period 3 has electrons in 3 levelsnumberenergylevelsoccupied
Group (column)
  • linked to the number of electrons in the outer level
  • which take part in chemical reactions
linkednumberelectronsouter
•
  • Elements are divided into metals
  • which lie on the left and centre of the table and are shiny
  • good conductors of heat and electricity
  • and malleable
  • non-metals
  • which lie on the right
  • and noble gases
  • which lie in group 18 and are very stable because their outer level is full
Elementsdividedmetalsleft
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