Science and Technology for UPSC Examinations [Chemistry] Part 9- Notes on Alkali metals

This family is Group 1 of the periodic table and includes lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs), and francium (Fr).

  • Hydrogen is a nominal member because it rarely shows any similar property. So Hydrogen is not among the alkali metals.
  • Alkali metals are all highly reactive and are never found in elemental forms in nature.
  • They are usually stored immersed in mineral oil or kerosene (paraffin oil) because of their high reactive nature.
  • They have low melting points and densities.
  • All alkali metals have silver color except caesium which has a golden color.
  • the react with halogens and make salts for example NaCl (table salt)
  • They react with water and make Hydroxides for example NaOH
  • Potassium and rubidium are naturally weakly radioactive elements and they each contain a long half-life radioactive isotope.
  • Under standard conditions Lithium is the lightest metal and the least dense solid element.
  • Lithium carbonate is used in use in psychiatry
  • Organolithiums are also used in polymer synthesis and for creating carbon-carbon polymers.
  • Lithium batteries are disposable (primary) batteries with lithium metal or lithium compounds as an anode, while the Lithium ion batteries are high energy-density rechargeable batteries.
  • Al-Li alloys are used in aeronautics.
  • The sodium vapor lamp uses sodium in an excited state to produce light.
  • Alkali metal as the Na+ ion is vital to animal life.
  • Molten sodium is used as a coolant in some types of nuclear reactors.
  • It decreases in blood pressure and decreases in sodium concentration sensed within the kidney result in the production of rennin which in turn helps in secretion of ant diuretic hormones
  • Animal cells, potassium ions are vital to cell function. They participate in the Na-K pump and in helping to restore the body’s total amount of fluid.
  • Sodium is the chief cation in fluid residing outside cells in the mammalian body
  • Low sodium intake may lead to sodium deficiency which is known as hyponatremia.
  • About 93% of the world potassium production is consumed by the fertilizer industry
  • Potassium chloride is used in execution by lethal injection.
  • Potassium vapor is used in several types of magnetometers
  • Caesium is one among the five metals which are liquid at room temperature. These are Mercury (melting point −39 °C), Francium (27 °C) caesium (28 °C), Gallium (30 °C) & rubidium (39 °C)
  • Caesium has been used in the petroleum Industry exploration as caesium formate.
  • The caesium atomic clocks use the resonant vibration frequency of caesium-133 atoms as a reference point. Precise caesium clocks measure frequency with an accuracy of from 2 to 3 parts in 1014, which would correspond to a time measurement accuracy of 2 nanoseconds per day, or one second in 1.4 million years.