Question

Write the electronic configuration of Mg (Z=12) and predict its group number and period number in the modern periodic table.

Answer 1

Step 1:

The horizontal rows of the long form of the modern periodic table are called periods. The vertical columns of the long form of the modern periodic table are called groups.

The distribution of electrons into orbits of an atom is called electronic configuration.

Step 2:

The atomic number of Magnesium ($\mathrm{Mg}$) is 12. The electrons are filled in an electron shell.

The electronic configuration of Magnesium is 2,8,2. The two electrons are filled in the innermost K-shell.

The eight electrons are filled in L-shell and two electrons are filled in outermost M-shell.

Magnesium belongs to group 2 and period 3.