From the symbol ${}_{12}{}^{24}\mathrm{Mg}$ , state the mass number, the atomic number and electronic configuration of magnesium.

In the representation of a symbol, the superscript indicates the mass number and the subscript indicates the atomic number.

Hence, for Magnesium (Mg)

• Atomic number =12
• Mass number =24.

For electronic configuration, the value of number of electrons is required. This can be calculated from atomic number.

• Atomic number= Number of protons= Number of electrons in a neutral atom
• Therefore, the number of electrons= 12
• Electronic configuration of Magnesium is 2,8,2