Chemistry, 10.07.2019 09:00 cassidyschmuzler

In thionyl chloride, cl2so (s is the central atom), the formal charge on sulfur and number of lone pairs on sulfur are, respectively, (assume all the atoms obey the octet rule) g

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Answer from: kevinyanyp7egif

Sulfur in the thionyl compound will have the formal charge or +1 and has two lone electrons or one lone pair.

Further ExplanationLewis Structures

In order to determine the formal charge and number of lone pairs, it is imperative to draw the Lewis structure first. The steps in drawing the lone pairs are:

Get the total number of valence electrons by adding the number of valence electrons of each atom in the compound.Determine the central atom.Place the other atoms around the central atom and connect each to the central atom by a single bond. For every single bond, 2 electrons from the total valence electrons are shared. Distribute the remaining valence electrons to the terminal atoms. Start by distributing to one terminal atom until the atom has an octet then move to the next terminal atom. If all terminal atoms have an octet, the remaining electrons will be placed in the central atom.

For thionyl chloride, the central atom is sulfur and the total number of valence electrons is:

Cl = 7 × 2 = 14

S = 6

O = 6

Total Valence Electrons = 14 + 6 + 6 = 26 electrons. Following the steps above, the resulting Lewis structure is shown in the attachment.

Once the Lewis structure is known, the number of lone pairs in the central atom can be known. For thionyl chloride, it can be seen that there are two unshared electrons in S. Therefore, S has one lone pair.

Formal Charges

The relative distribution of electrons in a molecule can be described through the formal charges of each atom. The formal charge describes how many electrons there are in an atom compared to how many electrons it has if it were not bonded. For a molecule to have a stable structure, the formal charges of all the atoms must be at the lowest possible values.

The formula to determine the formal charge is:

Formal Charge = # valence electron for the isolated atom - (# bonds + non-bonding electrons)

For the thionyl compound, the formal charge of S is determined using the following equation and by looking at the Lewis Structure:

Valence Electrons of a Sulfur atom = 6Number of bonds around Sulfur = 3Number of non-bonding electrons on Sulfur = 2

Formal Charge of S = 6 - (3+2)

Formal Charge of S = +1

This means that sulfur has less electrons around it in the molecule than it has as an isolated atom.

Learn MoreLewis Structure Valence Electrons

Keywords: formal charge, lone pairs

In thionyl chloride, cl2so (s is the central atom), the formal charge on sulfur and number of lone p

Answer from: tommy4260

In thionyl chloride, the formal charge on sulfur and number of lone pairs on sulfur are $\boxed{+1}$ and $\boxed{1}$ respectively. (For structure, refer to the attached image).

Further explanation:

Lewis structures are used to describe bonding between various atoms in covalent molecules. Such diagrams are also known as electron dot diagrams, Lewis dot structures or Lewis dot formula.

Lewis structure of $\text{Cl}_2\text{SO}$ (Refer to the structure in the attached image):

The total number of valence electrons of $\text{Cl}_2\text{SO}$ is calculated as,

$\begin{aligned}\text{Total valence electrons}=&\text{(2)(valence electron in Cl)}\\&+\text{(1)(valence electron in S)}\\&+\text{(1)(valence electron in O)}\\ =&\text{[(2)(7)+(1)(6)+(1)(6)]}\\=&26\end{aligned}$

Sulfur forms one double bond with an oxygen atom and two single bonds with two chlorine atoms. Out of these 26 electrons, eight electrons are utilized in formation of one S-O double bond and two S-Cl single bonds and 18 electrons are left behind. Three lone pairs are present on each chlorine atom, two lone pairs are present on oxygen atom and one lone pair is present on sulfur atom.

Formal charge is the charge acquired by atom in a molecule by assuming that the chemical bonds are shared equally between the two atoms, no matter what their electronegativities are.

The formula to calculate the formal charge on an atom is as follows:

$\begin{aligned}\text{Formal charge}=&\text{(total number of valence electrons in the free atom)}\\&-\left(\text{total number of non-bonding electrons}\right)\\&-\left[\dfrac{\left(\text{total number of bonding electrons}\right)}{2}\right]\end{aligned}$ ...... (1)