Basic chemistry

 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

 Modern Periodic table Modern Periodic Law :  The recent work has established that the fundamental property of an atom is atomic number and not atomic weight. Therefore, atomic number is taken as the basis of the classification of the elements. The modern periodic law was given by Moseley, it may be stated as : ''The properties of elements are periodic functions of their atomic number". Modern periodic table is also called long form of the periodic table or Bohr’s table. In this table, the elements are arranged in order of their increasing atomic number. It consists of 4 blocks (s, p, d and f), 18 groups numbered from 1 to 18 and 7 periods numbered from 1 to 7. Short tricks to learn periodic table  Blocks : The periodic table is divided into four main blocks (s, p, d and f) depending upon the subshell to which the valence electron enters into.  (1) Elements of group 1 and 2 constitute s-Block.   (2) Elements of group 13, 14, 15, 16, 17, 18 constitute p-Block.   (3)