Write Lewis structures that obey the octet rule for the...

Write Lewis structures that obey the octet rule for the following species. Assign the formal charge for each central atom. a. $\mathrm{POCl}_{3}$ e. $\mathrm{SO}_{2} \mathrm{Cl}_{2}$ b. $\mathrm{SO}_{4}^{2-}$ f. $\mathrm{XeO}_{4}$ c. $\mathrm{ClO}_{4}^{-}$ g. $\mathrm{ClO}_{3}^{-}$ d. $\mathrm{PO}_{4}^{3-}$ h. $\mathrm{NO}_{4}^{3-}$

Write Lewis structures that obey the octet rule for the following species. Assign the formal charge for each central atom.
a. $\mathrm{POCl}_{3}$
e. $\mathrm{SO}_{2} \mathrm{Cl}_{2}$
b. $\mathrm{SO}_{4}^{2-}$
f. $\mathrm{XeO}_{4}$
c. $\mathrm{ClO}_{4}^{-}$
g. $\mathrm{ClO}_{3}^{-}$
d. $\mathrm{PO}_{4}^{3-}$
h. $\mathrm{NO}_{4}^{3-}$

Key Concepts

Lewis Structures

Lewis structures are diagrams that represent the bonding between atoms in a molecule and the lone pairs of electrons that may exist. They are essential for visualizing how atoms share or transfer electrons to achieve a stable electronic configuration. By using dots for electrons and lines for bonds, these structures facilitate the prediction of molecular shapes, reactivity, and the placement of electrons in chemical species.

Octet Rule

The octet rule is a chemical guideline stating that atoms tend to form bonds until they are surrounded by eight valence electrons, achieving a noble gas configuration. While most common for second-period elements, this rule helps predict the number and type of bonds in a molecule, although some atoms in higher periods can expand their octet.

Formal Charge

Formal charge is a bookkeeping tool used to determine the distribution of electrons in a molecule by comparing the number of electrons an atom owns in a Lewis structure to the number it would possess in its neutral state. Calculating formal charges assists in identifying the most plausible structure of a molecule, by minimizing the overall formal charges and ensuring that negative charges reside on the more electronegative atoms.

Expanded Octet

Expanded octet refers to the ability of atoms, usually those in period 3 and beyond, to accommodate more than eight electrons in their valence shell by utilizing available d-orbitals. This concept is crucial when drawing Lewis structures for molecules that include elements like phosphorus, sulfur, or xenon, which often form compounds with more than four bonds.

Transcript

00:01 Okay, if phosphorus is your central atom, you're going to have three chlorine and an oxygen coming off.

00:07 You've got a total of 32 valence electrons to work with, so that means you're going to have an octet on everything.

00:15 And then to calculate the formal charge, formal charge is the number of valence electrons minus the number of dots and lines on that particular atom.

00:29 So phosphorus has five valence electrons minus four lines, so that means you have a plus one as its formal charge.

00:36 For b, when we're looking at sulfate, you've got sulfur in the middle with four oxygens coming off of it.

00:42 And we've got a total of 32 valence electrons to work with, so that means you'll have an octet.

00:48 On everything, this is in a bracket with a negative two charge.

00:52 The formal charge on the sulfur is going to be six valence electrons minus four lines, so you have a positive two.

00:59 For c, you're going to have chlorine in the middle with your four oxygen attached.

01:06 You have 32 valence electrons to work with, so you're going to have an octet on everything.

01:13 This is in a bracket with a negative one charge on the outside.

01:16 Your formal charge is going to be seven valence electrons minus four lines, so you have a positive three on the chlorine.

01:23 Then in d, you have phosphorus in the middle with four oxygen attached.

01:29 Have 32 valence electrons to work with.

01:32 So that's why you're going to satisfy the octet rule on everything.

01:36 This is in a bracket with a negative three charge on the outside.

01:39 That phosphorus is five valence electrons minus four lines.

01:43 That's a positive one formal charge.

01:45 Then for e, you're going to have sulfur in the middle with three, i'm sorry, two chlorine and two oxygen attached...

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