Bohr models notes
the number of periods shows you the number of

The number of periods shows you the number of

Electron Shell

Explanation:

Modern periodic table is divided into Groups and Periods.

A period is the horizontal row of the periodic table. There are seven periods in the periodic table.

It describes the following :

A group is the vertical column of the periodic table . There are 18 groups in total.

It describes the following :

The group number of the element is same as the number of electrons in the outermost shell.

The element having group 1 has = 1 electron in outer shell (example Na, K)

The element having group 2 has = 2 electron in outer shell (example Ca, Mg)

The element having group 0 has = full outer shell (example Ne Xe). these are also known as noble gases