The modern periodic table

• The modern periodic table


  This periodic table was proposed by Henry Moseley by increasing order of atomic number
• Moseley's Work


  Moseley's work showed that the properties of an element were determined by its atomic number, not its mass.
• He arranged the elements in rows called periods and columns called groups.
• Groups

  • vertical arrangement in the periodic table
  • There are 18 groups
  • They are divided into two main group and subgroups
  • Elements in the same group have similar properties
  • Groups no = no of valence electron only for main group
• Major groups

  • Group IA - Alkali metals except hydrogen
  • Group IIA - Alkaline earth metals
  • Group VB - Pnicogens
  • Group VIB - Chalcogens
  • Group VIIB - Halogens
  • Group VIIA - Noble(inert gases)
• Periods

  • horizontal arrangement in the periodic table
  • There are 7 periods
  • Period no = no of shells
• Periods

  1. period 1 contains 2 elements, very short period
  2. period 2 & 3 contain 8 elements, 1st & 2nd short periods, respectively
  3. period 4 & 5 contain 18 elements, 1st & 2nd long periods, respectively
  4. period 6 & 7 contain 32 elements, very long period
• Electron configuration 


  Electron configuration the arrangement of electrons in an atom.
• Ground state electron configuration

  The lowest energy arrangement of the electrons in an atom is called the ground state electron configuration

  1 represents the main shell

  s represents the sub shell (s, p, d, f)

  2 (superscript) represents no electron in that subshell.

  
• Orbital


  Orbitals are regions around an atom's nucleus that describe the probability of finding an electron.

  They are s, p, d, f
• Orbitals max electron


  s - 2

  p - 6

  d - 10

  f - 14
• Classification of elements


  Based on their electron configuration elements are classified into

  s, p, d, and f blocks
• s-block elements

  If the last electron enters into s-orbital, the elements are called as s-block elements.
• p - block elements

  If the last electron enters into the p-orbital, the elements are called as p-block elements.
• d-block elements

  If the last electron enters into d orbital, the elements are called d-block elements (except Thorium)
• f-block elements

  If the last electron of the elements enters into f-orbital, they are called f-block elements.
• The general electron configuration of elements in each block