Chapter 23, Problem 79A

Interpretation Introduction

Interpretation : To illustrate the dot structure of fluoride ions from a fluorine atom and hydroxyl ions from hydrogen and oxygen.

Concept Introduction : Lewis dot structure represents the covalent bonds as well as the lone pair of electrons in the molecule. Lewis dot structure is mainly based on the octet rule. The electrons are arranged around the atom in such a way that they obtain the octet configuration and are also capable of forming the covalent bond with the other atoms in the molecule.

Answer to Problem 79A

  

  

Explanation of Solution

Fluorine has an electronic configuration ${\text{1s}}^{\text{2}}{\text{2s}}^{\text{2}}{\text{2p}}^{\text{5}}$ , which means that there are seven valency electrons in the outermost orbital. When we consider the fluoride ion there will be an addition of one electron so that it will attain the octet configuration. Therefore, the number of electrons in the valency shell will be 8 for fluoride ions.

The electronic configuration of oxygen is ${\text{1s}}^{\text{2}}{\text{2s}}^{\text{2}}{\text{2p}}^4$ . This means that there are 6 valency electrons in oxygen and the electronic configuration of hydrogen is ${\text{1s}}^1$ means that it has only one electron in its valence shell and since there is a negative charge one more electron gets added. Therefore, the Lewis structure of ${\text{OH}}^{\text{-}}$ will have total 8 electrons in total.

Conclusion

From the above example of ${\text{OH}}^{\text{-}}$ it is clear that the Lewis structure explains the electronic representation of elements and also the pairing of electrons to form molecules. It also gives the number of covalent bonds between the atoms in a given molecule.