PERIODIC ELEMENTS
ALKALI METALS

 



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Chemistry of Alkali Metals


The elements belonging to group 1 of periodic table are called alkali metals. They are called alkali metals because they readily dissolve in water to form hydroxides which are strongly alkali in nature.

General characterstics of Alkali metals:-

  1. All alkali metals are silver white in colour, soft and light metals.
  2. All alkali metals have one electron in their outermost s-orbital. Thus their general electronic configuration may be written as [Noble Gas] ns1.
  3. Alkali metals have the largest atomic and ionic radii in their respective periods. On moving down the group the atomic and ionic radii increase.
  4. They have the lowest ionization enthalpy in each period. On moving down the group their ionization enthalpies decrease.
  5. They are soft and have low melting and boiling points.
  6. Their densities are very low as compared to other metals. Li, Na and K are even lighter than water. However, their densities increase on moving down the group.
  7. All alkali metals are strongly electropositive metals in character. The metallic character increases down the group.
  8. All alkali metals exhibit on oxidation state of +1 of their compounds.
  9. All alkali metals impart characteristics flame colour when burnt .e.g. Na provides yellow colour to flame.
  10. Alkali metals shows photoelectric effect.
  11. Lattice enthalpies of alkali metals are very high.
  12. Chemically all alkali metals are very reactive in nature. They react with air, water, hydrogen, halogens and acids to produce various types of compounds.
  13. Alkali metals are strong reducing agents.