Periodic table

• Periodic Table


  An arrangement of the elements in the order of increasing proton (atomic) number
• Periodic Table


  • Classifies elements into periods and groups
• Period


  A horizontal row of elements
• Group


  A vertical column of elements
• Elements in the same group

  • Have the same number of valence electrons, thus have similar chemical properties
• Elements in the same period

  • Have the same number of electron shells
• From left to right across a period

  The elements change from metallic to non-metallic character
• Metalloids


  Elements found next to the imaginary diagonal line dividing metals from non-metals, have properties of both metals and non-metals
• Metals

  • Atoms are more likely to lose electrons to form cations (Groups 1, 2 and 13)
• Non-metals

  • Atoms are more likely to gain electrons to form anions (Groups 15 to 17)
• Alkali metals


  Group 1 elements
• Alkali metals


  • Soft, low density metals with low melting and boiling points, good conductors of electricity
• Down the group of alkali metals


  Melting and boiling points decrease, densities increase, reactivity increases
• Reaction of alkali metals with water


  Form soluble bases (alkalis) and hydrogen gas
• Reaction of alkali metals with water


  • Lithium
  • Sodium
  • Potassium
• Halogens


  Group 17 elements
• Halogens


  • Diatomic non-metals
• Down the group of halogens


  Melting and boiling points increase, colour intensities increase, reactivity decreases
• Halogens undergo displacement reactions with halide solutions
• Noble gases


  Group 18 elements
• Noble gases


  • Monoatomic non-metals, colourless gases at room temperature, low melting and boiling points, insoluble in water, unreactive or inert
• Noble gases have fully filled valence electron shells, so they do not lose, gain, or share electrons