(a) What are ‘groups’ and ‘periods’ in the ‘periodic table’?

CBSE Class 10 CBSE Class 10 Science
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1

(a) What are ‘groups’ and ‘periods’ in the ‘periodic table’?

(b) Two elements M and N belong to group I and II repectively and are in the same period of the periodic table. How do the following properties of M and N vary ?

  1. Size of their atoms.
  2. Their metallic characters.
  3. Their valencies in forming oxides
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(a) Horizontal rows in the periodic table are called periods. The vertical columns in the
periodic table are called groups.

(b)

  1. Size of the atoms increase as we go from left to right because extra electron is added in the same valence shell due to which nuclear charges increases and which pulls the electrons towards itself and size decreases.

  2. Metallic character decreases when we move from left to right since, the size decreases the tendency of the above to denote the outermost electrons.

  3. 1,2