Preodic classification

 1. Introduction

  The periodic table can be defined as the table that classifies

  All known elements according to their properties

  Arba the India gamer

  Grouped together in a single vertical column

  The diffusion elements are separated from each other.

  2. Professional Development

  Vertical table

  All previous attempts to classify elements were

  Is based on their atomic weight.

  2.1 Dobereiner Triads

  In 1829, Dobriner classified some elements into groups

  Three of three are called.  Three elements were the same in a triad.

  chemical properties.  When there were elements in a triad

  Arranged in order to increase the atomic weight, atomic

  The weight of the middle element was found to be approx.

  Equivalent to the arithmetic mean of the other two elements.

  1. Triad Iron Cobalt Nickel Means 1

  And third

  On.  wt 55.85 58.93 58.71 atomic mass

  Almost the same

  2. Triad Lithium Sodium Potassium

  On.  wt 23 39 23

  2

  397 

  4

  3. triad chlorine bromine iodine

  On.  wt 35.5 80 127 25.81

  2

  1275.35 

  4

  4. Triad Calcium Strontium Barium

  On.  wt 40 87.5 137 5.88

  2

  17740 

  4

  2.2 Newland's law of Auckland

  In 1865, an English chemist, John Alexander Newlands

  saw that

  When lighter elements were arranged in their order

  Increasing atomic mass, properties of every eighth

  The elements were the same as the eighth,

  Note a musical scale.  This generalization was named

  Newlands law element of Aucklands li bb c n o f

  L curve

  (A) change with a period

  Over a period, the ionisation concentration increases.

  Break from left to right where atoms have something-

  What stable configuration.  Can be seen trend

  Easily 

  And reduction of nuclear ready.  Both factors increase

  Attraction force towards nucleus and consequently, more

  And more energy is required to remove electrons and

  Therefore, ionization penetration increases.

  (b) differentiation with a group

  Upon moving the group, the atomic size increases gradually

   element.  On the strength of this

  The attraction to the valence electrons decreases and

  Therefore the ionization enthalpy value is reduced.

  I.E./I.P of 4.5 units.

  It is measured in units of electron volts (eV) per atom or kg.

  Calories per mole (kcal mol-1) or kg joules per mole (kJ mol-1).

  An electron volt is the energy acquired by an electron while

  Operates under a potential difference of one volt.

  1 electron volt (EV) per atom

  = 3.83 × 10–20 cal per atom

  = 274.4849 × 10–19 J per atom (1 cal = 4.184 J)

  = 3.83 × 10–20 × 6.023 × 1023 cal mol-1 = 23.06 kcal mol - 1 = 1.602 × 10–19 × 6.023 × 1023 J mol - 1 = 96.49 kJ mol - 1  1 electron volt (eV) per atom.

  = 23.06 kcal mol-1 = 96.49 kJ mol-1 significant digits

  * Decreased size increases ionization energy

  Of an atom or an ion

  * Decreased screening increases ionization energy

  effect.

  * Increasing atom increases ionization energy

  Charge

  * Atomic energy increases if the atom is half full

  And fully filled orbitals

  * Penetrating power of orbitals is in order

  s> p> d> f

  increases

  Decreases

  Ionization

  Energy

  Period

  group

  Electron guy enthalpy

  

  Turn it into a negative ion, which is the Thalapi change.

  With this process the electron gain is defined as

  E n t h a l p y (tegH).  Electron gain bag provides a solution

  The ease with which an electron combines to form an atom

  As represented by ions

  X (g) + e- (X– (g)

  

  The atom may be either endothermic or exothermic.  For

  When an electron is added, the energy of many elements is released.

  Thalapi is negative in atomic and electron gain.  For

  Example, group 17 elements (halogen) are too many

  Negative electrons receive thalapes because they can receive

  A raised static elite gas electronic configuration

  Electron.  On the other hand, noble gases have large positives.

  The electron gets entry because the electron has to enter

  Leading to the next higher principal quantum level

  Unstable electronic configuration.

  Transformation of Electron Gain Enthalpy

  (A) change with a period

  The electron gain thalap becomes more and more negative

  Left to right over a period.  This is due to the size reduction

  And increase in atomic charge as atomic number

  Increases over a period.  Both these factors are in its favor

  Addition of an extra electron due to the extra force of

  Attraction by nucleus to incoming electron.

  (b) differentiation with a group

  The electron enters the gain, in general, decreases

  Negative from top to bottom in a group.

  This is due to an increase in size when a group is taken down.

  Vertical classification