What are the families and groups in periodic table?
In the periodic table, periods are the rows of the table, and
groups are the columns of the table. All the elements on a column
(group) have similar properties such as similar reactivity due to
the fact that they have same valence shell electron configurations.
meaning that the number of electrons present in the outer most
shell of all these elements are the same. Rows show the number of
electron shells around that element ( Bohr theory), or in advance
term, it represents the principle quantum number, which is the
total number of energy packets around the atom.