يوليو 18th, 2018

 

Ionization energy

Ionization energy

(or potential) of an element is defined as “The amount of energy required or needed to remove an electron from the neutral gaseous atom to form unipositive ion , for example Na → Na+ + e– + energy

This is measured in electron volts per atom or kJ mol-1. For example IE of Na is 495 kJ mol-1.

Trends in ionization energy of elements.

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Characteristics of periods and groups of a periodic table

Characteristics of periods and groups of a periodic table

Characteristics of periods

1 –  Valence electrons. On moving from left to right in a period, the number of valence electrons increases from 1 to 8 (except first period where the increase is from one to two only).

  Na         Mg         Al          Si            P           S           Cl          Ar

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Long form or Modern form of periodic table

Long form or Modern form of periodic table

The modem form of period table is based on increasing order of atomic number. General features of the table is as follows:

1 –  There are 18 vertical columns which arc called groups. They are numbered in the old form by IA, IB, IIA, IIB, … VIIA, VIIB VIII and 0 (zero) and in the new…

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