Question

Chlorine tends to form only one covalent bond because it needs just one electron to complete its octet. What are the Lewis structures for the simplest compound formed by chlorine with (a) nitrogen, (b) carbon, (c) sulfur, and (d) bromine?

Short answer

The simplest compounds formed and their Lewis structures are: (a) nitrogen trichloride (NCl3) with nitrogen as the central atom bonded to three chlorine atoms, (b) carbon tetrachloride (CCl4) with carbon as the central atom bonded to four chlorine atoms, (c) sulfur dichloride (SCl2) with sulfur as the central atom bonded to two chlorine atoms, and (d) bromine monochloride (BrCl) with a single bond between bromine and chlorine.

Step-by-step solution

Understanding Electron Requirements for Chlorine

Recognize that chlorine (Cl) has seven valence electrons and needs only one more electron to complete its octet. In the Lewis structure, chlorine is illustrated with seven dots representing its valence electrons, with one dot alone ready to form a bond.

Drawing Lewis Structure with Nitrogen

Nitrogen (N) has five valence electrons and needs three more to complete its octet. Pairing it with chlorine, chlorine can share one electron with nitrogen. However, since nitrogen needs to make a total of three bonds to complete its octet, it will have to bond with three chlorine atoms, leading to the formation of nitrogen trichloride (NCl3). The Lewis structure will show nitrogen in the center with three single bonds each connected to a chlorine atom.

Drawing Lewis Structure with Carbon

Carbon (C) has four valence electrons and needs four more to complete its octet. Carbon can make four bonds, and to satisfy chlorine's requirement for one additional electron, carbon will bond with four chlorine atoms to form carbon tetrachloride (CCl4). The Lewis structure will depict carbon in the center with four chlorine atoms each connected by a single bond.

Drawing Lewis Structure with Sulfur

Sulfur (S) has six valence electrons and needs two more to complete its octet. To form a stable compound with chlorine, sulfur can bond with two chlorine atoms, resulting in sulfur dichloride (SCl2). The Lewis structure will show sulfur in the center connected to two chlorine atoms with two single bonds.

Drawing Lewis Structure with Bromine

Bromine (Br), like chlorine, has seven valence electrons and needs only one to complete its octet. When bromine and chlorine combine, they form a diatomic molecule sharing one pair of electrons, resulting in bromine monochloride (BrCl). The Lewis structure for this molecule will depict a single bond between bromine and chlorine.

Key concepts

Covalent Bonds

Imagine atoms are like people who are happier when they share things; in chemistry, we call this sharing a 'covalent bond.' A covalent bond is when two atoms share pairs of electrons. This sharing allows them to stick together, like friends holding hands. Chlorine, for example, is one electron shy of being really happy—it wants to fill its outer shell, like completing a circle of friends. So, it shares one electron with another atom. This kind of bonding is a fundamental concept behind the molecules that make up our world.

Picture a molecule of water (H₂O): the oxygen atom shares electrons with two hydrogen atoms. This sharing forms covalent bonds, creating a V-shaped molecule that's essential for life. It's through covalent bonding that chlorine pairs up with other atoms like nitrogen, carbon, and sulfur in our exercise, making new compounds. Even the bond it forms with its twin, bromine, is a covalent bond—they share electrons like a perfect match.

Octet Rule

The 'octet rule' is kind of like the golden rule of bonding—it's the idea that atoms are the most stable and happy when they have eight electrons in their outer shell, like an octopus with eight arms. Think of atoms like people at a dance, looking to have a full circle of eight partners to dance with. Atoms like chlorine want to fill their outer shell to have a perfect octet.

When we look at our exercise, elements such as chlorine, nitrogen, and carbon form bonds to achieve this complete set of eight valence electrons. Nitrogen grabs three chloride partners to dance with, giving it that full circle of eight electrons. Carbon does the same but needs four chlorine partners for a complete set. Sulfur settles with two, and bromine pairs with another to fill its dance card. All these interactions are guided by the octet rule which helps us predict how atoms will bond together.

Valence Electrons

Valence electrons are like the outermost pieces of an atom's jigsaw puzzle—those pieces that actually connect with other puzzles. They are the electrons in the outer shell of an atom and are crucial players in the game of bonding. Chlorine, for instance, has seven of these special pieces, and to complete its puzzle, it needs to add just one more.

In the compounds mentioned in our exercise, we see chlorine eager to complete its set of valence electrons. Nitrogen, Carbon, Sulfur, and Bromine—each of these elements brings different numbers of valence electrons to the table, and by sharing, they're trying to complete their own puzzles as well. For instance, Carbon comes with four electrons ready to bond, but to finish its puzzle, it joins with four chlorines. All these different combinations of sharing are the essence of chemical bonding and are determined by the number of valence electrons an atom has.