Physical Properties -

• Physical properties of alkali metals:

  • Soft and can be cut with a knife
  • Have relatively low melting points
  • Have low densities, with the first three (lithium, sodium, and potassium) able to float on water
• The melting points of alkali metals decrease as you move down Group 1:

  • Lithium has the highest melting point
  • Sodium has a lower melting point than lithium
  • Potassium has a lower melting point than sodium
  • Rubidium has a lower melting point than potassium
  • Cesium has the lowest melting point in Group 1