Question

Write a formula for each of the following ionic salts using the Lewis symbols of the ions. (a) \(\mathrm{LiCl}\) (b) \(\mathrm{BaCl}_{2}\) (c) \(\mathrm{BaS}\)

Short answer

The Lewis structures for the given ionic salts are [Li]+[Cl]− for \(\mathrm{LiCl}\), [Ba]2+[Cl]−[Cl]− for \(\mathrm{BaCl}_{2}\), and [Ba]2+[S]2− for \(\mathrm{BaS}\).

Step-by-step solution

Identify the ions

Based on the periodic table, identify the ions in each ionic salt. Li in \(\mathrm{LiCl}\) is a +1 cation, Cl is a -1 anion. Ba in both \(\mathrm{BaCl}_{2}\) and \(\mathrm{BaS}\) is a +2 cation, Cl in \(\mathrm{BaCl}_{2}\) is a -1 anion, and S in \(\mathrm{BaS}\) is a -2 anion.

Write the Lewis symbols

The Lewis symbol for Li+ would be [Li]+, Cl- would be [Cl]−, Ba2+ would be [Ba]2+, and S2− would be [S]2−.

Formulate the ionic salts

Next, we combine the cations and anions to form the ionic salts. The Lewis structure of \(\mathrm{LiCl}\) would be [Li]+[Cl]−. The Lewis structure of \(\mathrm{BaCl}_{2}\) would be [Ba]2+[Cl]−[Cl]− because there has to be two chloride ions for each barium ion to balance out the charges. The Lewis structure of \(\mathrm{BaS}\) would be [Ba]2+[S]2−, due to the balancing out of charges.

Key concepts

Chemical Bonding

Understanding chemical bonding is crucial for making sense of how atoms come together to form compounds. At its core, chemical bonding is about atoms achieving a more stable electronic configuration, typically that of the noble gases with a full outer shell of electrons. There are three primary types of chemical bonds: ionic, covalent, and metallic.

Ionic bonding occurs between metals and non-metals when one atom, usually a metal, loses electrons to become a positively charged ion, while the other atom, usually a non-metal, gains those electrons to become a negatively charged ion. These ions are then attracted to each other due to their opposite charges. In the exercise, lithium (Li), barium (Ba), and chlorine (Cl) are involved in ionic bonds, where Li and Ba are cations (positive ions) and Cl is an anion (negative ion).

Writing Chemical Formulas

Writing chemical formulas is akin to an art in the world of chemistry. It involves representing the proportions of atoms that constitute a particular chemical compound. When writing formulas for ionic compounds, the goal is to combine cations and anions in a ratio such that the overall electric charges cancel out, leading to a neutral compound.

When writing the chemical formula, it's important to identify the charge on each ion first, a task that can be accomplished by examining the periodic table of elements. For instance, lithium has a +1 charge after losing one electron, and chlorine has a -1 charge after gaining an electron, resulting in the formula \(\mathrm{LiCl}\). For barium chloride (\(\mathrm{BaCl}_2\)), barium gives up two electrons to form a +2 charged ion, requiring two chlorine ions to balance the charges. The exercise of writing chemical formulas not only requires knowledge of charges but also the ability to balance these charges to achieve neutrality.

Periodic Table of Elements

The periodic table of elements is an invaluable tool for chemists, encapsulating a wealth of information about the elements and their relationships. Most importantly, it provides insight into an element's electron configuration, which is essential for understanding chemical bonding and reactivity.

Elements are organized into groups and periods, with elements in the same group typically having similar chemical properties due to their similar valence electron configurations. For example, the alkali metals, found in group 1, all have one valence electron that they are ready to give up in order to bond with other elements. Understanding the periodic table is indispensable for solving chemical problems, such as identifying the ionic charges for lithium, barium, and chlorine as done in the original exercise, which subsequently allows for the successful writing of chemical formulas for ionic compounds.