Problem 123 - Chemistry: An Atoms-Focused Approach

Question

How many electrons are there in the covalent bonds surrounding the sulfur atom in the following species? (a) \(\mathrm{SF}_{4} \mathrm{O} ;\) (b) \(\mathrm{SOF}_{2} ;(\mathrm{c}) \mathrm{SO}_{3} ;(\mathrm{d}) \mathrm{SF}_{5}{-}.\)

Step-by-Step Solution

Answer

Answer: (a) 10 electrons, (b) 6 electrons, (c) 6 electrons, (d) 10 electrons.

Step 1: Understand covalent bonds and electron sharing in molecules

Covalent bonds are formed by the sharing of electrons between two atoms. Each atom contributes one electron to the shared pair (called bonding electron pair). Thus, there are two electrons in each covalent bond.

Step 2: Determine the number of covalent bonds around sulfur in each molecule

We need to find the total number of covalent bonds around the sulfur atom in each molecular species. (a) For \(\mathrm{SF}_{4} \mathrm{O}\), there are 4 covalent bonds with F atoms and 1 covalent bond with the O atom. Total covalent bonds: 4 + 1 = 5 (b) For \(\mathrm{SOF}_{2}\), there is 1 covalent bond with the O atom and 2 covalent bonds with F atoms. Total covalent bonds: 1 + 2 = 3 (c) For \(\mathrm{SO}_{3}\), there are 3 covalent bonds with the O atoms. Total covalent bonds: 3 (d) For \(\mathrm{SF}_{5}^{-}\), there are 5 covalent bonds with the F atoms. Total covalent bonds: 5

Step 3: Determine the total number of electrons in the covalent bonds

Multiply the total number of covalent bonds (found in Step 2) by 2, since there are two electrons in each covalent bond. (a) For \(\mathrm{SF}_{4} \mathrm{O}\), total electrons = 5 covalent bonds × 2 electrons/bond = 10 electrons (b) For \(\mathrm{SOF}_{2}\), total electrons = 3 covalent bonds × 2 electrons/bond = 6 electrons (c) For \(\mathrm{SO}_{3}\), total electrons = 3 covalent bonds × 2 electrons/bond = 6 electrons (d) For \(\mathrm{SF}_{5}^{-}\), total electrons = 5 covalent bonds × 2 electrons/bond = 10 electrons Therefore, the number of electrons in the covalent bonds surrounding the sulfur atom in each species are: (a) 10 electrons (b) 6 electrons (c) 6 electrons (d) 10 electrons

Key Concepts

Electron Sharing

In chemistry, covalent bonding is all about electron sharing between atoms. This occurs when two non-metal atoms come together, each contributing one electron to form a bond. A single covalent bond, therefore, consists of two electrons—one from each atom. This sharing leads to the formation of a stable electron pair, completing each atom's outer electron shell.
Covalent bonds are crucial for maintaining the integrity of a molecule by holding the atoms together.

• In molecules like \( \mathrm{SF}_{4} \mathrm{O} \), the sulfur atom shares four pairs of electrons with four fluorine atoms and one pair with an oxygen atom.
• This results in a total of five covalent bonds, each comprising two shared electrons, making a total of ten electrons surrounding the sulfur.

Understanding the principle of electron sharing helps us deduce the number of electrons involved in these bonds, providing insights into the molecule's structure and stability.

Sulfur Compounds

Sulfur plays a versatile role in forming diverse compounds thanks to its ability to use various oxidation states and bond with multiple elements. When sulfur forms compounds, it often exhibits the ability to bond with several atoms simultaneously.
Consider sulfur's compounds like \( \mathrm{SF}_{4} \mathrm{O} \) and \( \mathrm{SOF}_{2} \). In \( \mathrm{SF}_{4} \mathrm{O} \), sulfur makes covalent bonds with both fluorine and oxygen, demonstrating its preference for flexibility in bonding configurations.

• In \( \mathrm{SF}_{4} \mathrm{O} \), sulfur creates four bonds with fluorine atoms and one with an oxygen atom. This varied bonding ability is due to sulfur's placement on the periodic table, which allows it to work effectively with different elements.
• Similarly, in \( \mathrm{SF}_{5}^{-} \), sulfur is capable of forming five covalent bonds, all with fluorine, due to its expanded valence shell.

These sulfur compounds highlight the element's chemical diversity and its capacity to form multiple covalent bonds.

Molecular Geometry

Molecular geometry refers to the three-dimensional arrangement of atoms within a molecule. This shape is determined by the number of bonds and lone pairs surrounding a central atom, affecting the molecule's properties.
For example, sulfur compounds like \( \mathrm{SF}_{4} \) typically exhibit a "seesaw" geometry due to the four fluorine atoms and one lone pair on the sulfur atom. Meanwhile, \( \mathrm{SOF}_{2} \) is influenced by the geometry dictated by the arrangement of its two fluorines and one oxygen around sulfur.
Factors influencing molecular geometry include:

• The number of atoms bonded to the central atom
• The number of lone electron pairs on the central atom
• The repulsion between these electron pairs

This configuration impacts molecular polarity, reactivity, and interaction potential. Understanding these geometric configurations enables chemists to predict and explain the behavior of molecules in various chemical reactions and physical interactions.