Question

Write the electron - dot structure of magnesium and oxygen.

Answer 1

Hint: To draw an electron-dot structure for any element, we write its chemical symbol surrounded by a number of dots, which represents the number of outer shell or valence electrons of the atom. To draw the electron-dot structure of magnesium and oxygen, we need to know their electronic configuration, to determine the valence electrons in the atom of each element.

Complete Solution :
As we know that in an electron-dot structure, the dots represent the valence electron in an atom of the element. Let us find the valence electrons in a magnesium atom and an oxygen atom from their respective electronic configuration.

The atomic number of magnesium (Mg) is Z = 12. Its electronic configuration is \[1{{s}^{2}}2{{s}^{2}}2{{p}^{6}}3{{s}^{2}}\]. Thus, magnesium has two electrons in its valence shell, which it can lose to attain the electronic configuration of its nearest noble gas – neon. Thus, the electron dot structure of Magnesium is given as,
\[Mg:\]

The atomic number of Oxygen (O) is Z = 8. Its electronic configuration is \[1{{s}^{2}}2{{s}^{2}}2{{p}^{4}}\]. Thus, oxygen has six electrons in its valence shell and requires two electrons in order to acquire stability. Therefore, the electron - dot structure for oxygen is given as:
\[:\overset{\centerdot \text{ }\centerdot }{\mathop{O}}\,:\]

Note: 1. Electron - dot structures, also known as Lewis structures, or Lewis - dot diagrams, are diagrams that show the bonding between atoms of a molecule and the lone pairs of electrons that may exist in the molecule.
- The Lewis structures of molecules are written in accordance with the octet rule. According to this rule, all atoms in a formula will have a total of eight electrons in the valence shell except in the case of Hydrogen atoms. Hydrogen will have two electrons because only two electrons are needed to complete its shell as in case of helium (He).