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1 Chapter-1 PERIODIC TABLE The arrangement of elements in Periodic table made easy to study their properties. The elements are arranged in the increasing order of their atomic numbers. - Atomic number is equal to the number of electrons in the orbits ( or energy shells) of an atom. Modern periodic law - The physical and chemical properties of elements are the periodic functions of their atomic number . Modern Periodic Table has 18 Groups (vertical columns) and 7 Periods (horizontal rows). The elements belonging to a particular group have same number of valence electrons. The period number indicates the number of shells in the atom of an element. Modern Periodic table (Long form of Periodic table) valency No. of valenc e electro ns 1+ 2+ 3+ 4 3- 2- 1- 0 1 2 3 4 5 6 7 8 GROUP NUMBE R IA IIA IIIA IVA VA VIA VIIA 0 1 2 13 14 15 16 17 18 PERIOD 11 shell PERIOD 2 2 shells PERIOD 3 3 shells 3 4 5 6 7 8 9 1 0 1 1 1 2 He2 H- 1 Li 2,1 Be 2,2 Na Mg 2,8,1 B 2,3 2,8,2 C 2,4 N 2,5 O 2,6 Al Si P S 2,8, 3 2,8, 4 2,8, 5 2,8, 6 F 2,7 Ne 2,8 Cl Ar 2,8,7 2,8,8 PERIOD 4 4 shells K Ca 2,8,8 ,1 2,8,8, 2 Br Kr PERIOD 5 Rb Sr I Xe PERIOD 6 Cs Ba At Rn PERIOD 7 Fr Ra ALKAL I META LS ALKALI NE EARTH METAL S TRANSITION ELEMENTS (METALS) HALOGE NS NOB LE GASE S http://icsechemistry16.blogspot.com ICSE CHEMISTRY for Class X www.icsechemistry16.blogspot.com
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