CBSE Class 11-science Answered

The s-block of the periodic table of elements consists of the first two groups: the alkali metals and alkaline earth metals, plus hydrogen and helium. Except H all elements of s-Block elements are active metals. These elements are distinguished by the property that in the atomic ground state, the highest-energy electron is in an s-orbital. Except in hydrogen and helium, these electrons are very easily lost to form positive ions. The 1st A group is called alkali metals, and 2nd A is called alkaline earth metals. The other elements of the s-block are all extremely powerful reducing agents, so much so that they never occur naturally in the Free State. The properties are:

               1. They have +1/ +2 oxidation state.

   2. They form basic oxides

   3. They impart characteristic color to the flame

   4. Generally they form ionic salts with nonmetals.

   5. They have low ionization potentials.

   6. They have very small electron gain enthalpies.

   7. They are solids at room temperature (Cs is liquid at about at 35^oC)

   8. Their hydroxides are basic in nature.