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Unit 1                          Graduation of the properties of
Lesson2                          elements in the
                                 modern periodic table

                                 properties

Atomic size                      Electronegativity  Metallic and
                                                    non-Metallic

                                                      property

    Atomic size

 The atomic radius is a measure of the atomic
 size of the atom.
  Its unit is picometer (p).
(The picometer = part from million million

    parts of a meter 1 p = 10-12 m)

Graduation of the atomic size of elements in the periodic
table

             In Periods                      In Groups

  Atomic size decreases due to     Atomic size increases due to
increasing the attraction force    increasing number of energy
 between nucleus & electrons     10 levels

    2nd Prep. First Term
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