Basic chemistry

 COMPOUNDS OF ALKALI METALS  1. Sodium (Na) , Natrium  Extraction of sodium  : Down's Process  By Electrolysis of fused NaCl + CaCl 2 + NaF  At cathode (Iron Vessel) : Na+ +e– ⟶  Na(s)  At Anode (Graphite) : 2Cl–   →    Cl 2 + 2e–  (i) (CaCl 2 + NaF) is used to lower Melting point (8000 C) of NaCl to about 6000 C.  (ii) Aqueous sodium chloride cannot be used for preparing sodium by electrolysis. Because instead of metallic sodium, hydrogen gas will be liberated at cathode. Properties sodium , Natrium (i) sodium is a crystalline soft metal.  (ii) Highly reactive, so kept in kerosene.  (iii) Na dissolves in liquid NH3 to give blue solution.  Uses of sodium , natrium  (i) In the preparation of sodium amalgam (used as reducing agent)  (ii) In sodium vapour lamp, which emits monochromatic yellow light.  (iii) As heat transfer medium in nuclear reactors. 2. Sodium chloride NaCl Occurrence of sodium chloride (NaCl)  Sea water is the main source and also found in salt lakes. P

 ALKALI METAL  Alkali Metal are   lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr) 1.Physical state of alkali metal  One electron in outermost shell & General formula ns¹.   Francium is radioactive element.  All are silvery white.  Light soft, malleable and ductile metals with metallic lustre.   Alkali metals are paramagnetic, diamagnetic and colourless in form of ions. 2.Atomic size of alkali metal  Biggest in their respective period (except noble gas element)  Size increases from Li to Fr due to addition of an extra shell.  Li < Na < K < Rb < Cs < Fr 3. Softness of alkali metal  Alkali metals are soft because of-  (i) Large atomic size  (ii) BCC crystal structure (HCP in Li)  (iii) Loose packing (68% packing efficiency)  (iv) Weak metallic bond  Cs is the softest metal in s-block 4. Melting point and boiling point of alkali metal  Weak interatomic bonds are due to their large atomic radii and presence of only one valence elect