mendeelevs periodic table has how many periods n groups - Science - Periodic Classification of Elements

Question

mendeelevs periodic table has how many periods n groups?

Taruna Chopra · Accepted Answer

Mendeleev's periodic table contains nine vertical columns of
elements called 'groups'(are
numbered from I to VIII and zero) and seven horizontal rows
called 'periods'

The members of zero group were not discovered at the time of
Mendeleev

Each group except VIII has two sub-groups A and B The properties of
elements of a sub-group resemble each other more markedly than the
properties of those between the elements of the two
sub-groups