Chapter U2, Problem 12STP

Interpretation Introduction

Interpretation:

The electron domains that affect molecular shape of a covalent or molecular compound needs to be determined.

Concept introduction:

An electron domain around an atom is defined as the region of space around the atom where the probability of finding an electron is maximum.

It is known that a covalent bond is formed between two atoms by mutual sharing of two electrons. Thus, a bonded electron group represents the number of electron pairs involved in bond formation. Since an atom can contain one or more pairs of non-bonded electrons around it, hence, a non-bonded electron domain is the number of non-bonding electron pairs present around the atom.

The number of electron domains gives the number of spaces where electrons may be expected to be found around an atom. The arrangement of electron domains around the atoms in a molecule gives the molecule a definite shape which is known as the molecular geometry.

Answer to Problem 12STP

The third option, option (C) is the correct answer.

Explanation of Solution

Reason for Correct Option:

An electron is a sub-atomic particle having zero mass and one unit of negative charge. Since like charges repel each other, hence, an electron will repel another electron when the two electrons are brought in close contact. In order to minimize the repulsions, the electrons orient in such a way that there is minimum repulsion.

The electron domains around the atoms in a molecule determine the number of electrons around the atoms. These electrons repel each other and thus, orient themselves around the atoms in such a way that there is minimum repulsion between the electrons. This optimum orientation of all the electron domains around the atoms in a molecule confer the molecule its geometric shape.

Conclusion

Reasons for Incorrect Options:

An electron repels another electron when the two electrons are brought in close contact. The first and the second options, (A) and (B) provide partly correct answers, since electronic repulsions occur between both bonded and lone or non-bonded electrons equally.

The last option, (D) is completely incorrect since electrons have like or similar charges and similar charges repel each other, while opposite charges attract each other.