Question

Chlorine Bleach Chlorine combines with oxygen in several proportions. Dichlorine monoxide \(\left(\mathrm{Cl}_{2} \mathrm{O}\right)\) is used in the manufacture of bleaching agents. Potassium chlorate \(\left(\mathrm{KClO}_{3}\right)\) is used in oxygen generators aboard aircraft. Draw the Lewis structures for \(\mathrm{Cl}_{2} \mathrm{O}\) and \(\mathrm{ClO}_{3}^{-}\).

Short answer

Question: Draw the Lewis structures for Cl2O and ClO3- molecules. Answer: For Cl2O, the Lewis structure is: Cl::O - Cl For ClO3-, the Lewis structure is: \begin{align*} O^{-}\left(:::\right)-&Cl&-O^{-}\left(:::\right) \\ &| \\ &O^{-}\left(:::\right) \end{align*}

Step-by-step solution

Determine the valence electrons

First, we need to find out the number of valence electrons for each atom involved: Chlorine (Cl): 7 valence electrons Oxygen (O): 6 valence electrons

Calculate the total number of valence electrons for each molecule

For Cl2O: 2 Cl atoms x 7 valence electrons per Cl = 14 valence electrons 1 O atom x 6 valence electrons per O = 6 valence electrons Total valence electrons = 20 For ClO3-: 1 Cl atom x 7 valence electrons per Cl = 7 valence electrons 3 O atoms x 6 valence electrons per O = 18 valence electrons The ion has a single negative charge (-1), so we need to add 1 extra electron Total valence electrons = 26

Identify the central atom for each molecule

Typically, the element which is less electronegative and can create more bonds is picked as the central atom. For Cl2O, Chlorine (Cl) will be the central atom. For ClO3-, Chlorine (Cl) will also be the central atom.

Place the central atom and arrange the other atoms around it

Place the central atom (Cl) in the middle and arrange the other atoms around it. For Cl2O: Cl - O - Cl For ClO3-: 3 O atoms are arranged around the central Cl atom

Distribute the valence electrons considering octet rule

For Cl2O (20 valence electrons): 1. Connect the atoms using single bonds (2 electrons for each bond): Cl- O -Cl (6 electrons used) 2. Fill the octets for outer atoms: Remaining electrons: 20 - 6 = 14 electrons Oxygen atom needs 2 more electrons to complete its octet, so add 1 lone pair to it: Cl - O - Cl (8 electrons used) 3. Fill the octets for the central atom: Remaining electrons: 14 - 8 = 6 electrons Add 3 lone pairs on the central chlorine atom to complete its octet: Cl - O - Cl (6 electrons used) For ClO3- (26 valence electrons): 1. Connect the atoms using single bonds: Cl - O - O - O (6 electrons used) 2. Fill the octets for outer atoms: Remaining electrons: 26 - 6 = 20 electrons Three oxygen atoms need 6 more electrons each to complete their octets; add 3 lone pairs on each O atom: Cl - O - O - O (18 electrons used) 3. Fill the octets for the central atom: Remaining electrons: 20 - 18 = 2 electrons Add 1 lone pair on the central chlorine atom: Cl - O - O - O (2 electrons used)

Drawing the Lewis structures

For Cl2O: Lone pairs (:) and bonds (-) are represented as below: Cl::O - Cl For ClO3-: Lone pairs (::) and bonds (-) are represented as below: \begin{align*} O^{-}\left(:::\right)-&Cl&-O^{-}\left(:::\right) \\ &| \\ &O^{-}\left(:::\right) \end{align*}

Key concepts

Valence Electrons

Valence electrons are the electrons located in the outermost shell of an atom. These electrons are crucial because they determine how an atom can interact and bond with other atoms. For elements like chlorine and oxygen, these electrons play a significant role when forming chemical compounds.

For example, chlorine is in Group 17 of the periodic table and has 7 valence electrons. These electrons allow chlorine to gain one more electron to fill its outer shell, achieving a stable electron configuration similar to noble gases. Meanwhile, oxygen, found in Group 16, has 6 valence electrons and typically seeks to gain or share 2 more electrons to complete its octet.

• Chlorine (Cl) usually has 7 valence electrons.
• Oxygen (O) typically has 6 valence electrons.

Understanding valence electrons is the first step in drawing Lewis Structures, as it helps to determine how atoms will bond within a molecule.

Octet Rule

The octet rule is a chemical principle stating that atoms tend to combine in such a way that each atom has eight electrons in its valence shell. This gives the atom a structure similar to that of the noble gases, which are naturally stable.

In the case of chlorine (Cl) and oxygen (O), they bond with other atoms to fulfill this octet requirement. For example, when drawing Lewis structures for compounds like dichlorine monoxide (\(\mathrm{Cl}_2\mathrm{O}\)) or the chlorate ion (\(\mathrm{ClO}_3^-\)), we use the octet rule to help distribute the electrons. This ensures that each atom satisfies the octet rule, either by sharing, gaining, or losing electrons.

• Atoms form bonds so that each has an octet in its outermost shell.
• Exceptions include elements like hydrogen, which only need 2 electrons.

To apply the octet rule effectively, it's crucial to count all valence electrons correctly and arrange them so that each non-hydrogen atom in the molecule ends up with eight electrons.

Chlorine Compounds

Chlorine compounds are chemical compounds that contain chlorine with other elements. Chlorine, a halogen, is known for its reactivity, allowing it to form various compounds with diverse properties.

Examples such as dichlorine monoxide (\(\mathrm{Cl}_2\mathrm{O}\)) and potassium chlorate (\(\mathrm{KClO}_3\)) highlight chlorine's ability to combine with non-metals like oxygen. In these molecules, chlorine can act as both a central atom and a surrounding atom based on the specific compound.

• Dichlorine monoxide (\(\mathrm{Cl}_2\mathrm{O}\)) is used in making bleaching agents, showing its importance in industrial applications.
• Potassium chlorate (\(\mathrm{KClO}_3\)) is vital for oxygen generation, especially in closed environments like aircraft.

When drawing Lewis structures to represent these compounds, it's important to represent all bonds and electrons accurately, ensuring that the structure adheres to the octet rule for all atoms involved.