Question

Why do all elements of the same group have similar chemical properties?

Why do all elements inthesameperiod have different properties?

Answer 1

Chemical Properties are properties which depend on valence electronic configuration of each atom. If the valence configuration is same than the properties of all atom would be same. In the one particular group like group one i.e. alkali metal group have only one valence electron in its outermost shell . Thus every element of group posses same properties whereas in the same period, valence electrons of every element differ from each other.That's why elements in the same periods differ in chemical properties.