Video Transcript
Sodium ions have a charge of one plus and chloride ions have a charge of one minus. What is the formula of the compound formed from sodium ions and chloride ions?
The type of compound formed when positively charged ions, called cations, and negatively charged ions, called anions, are bound together through electrostatic interactions is an ionic compound. Ionic compounds exist as a three-dimensional network of cations and anions rather than as a discrete molecular unit. But despite being composed of many positively and negatively charged ions, an ionic compound as a whole has an overall neutral charge.
In order to answer this question, we need to write the chemical formula of an ionic compound that is composed of sodium ions and chloride ions. As ionic compounds exist as a three-dimensional network of ions, we know that this compound will contain many, many sodium ions and chloride ions. Therefore, it’s impossible to indicate the total number of sodium ions and chloride ions in the ionic compound using a chemical formula. So, instead of the chemical formula indicating the total number of sodium ions and chloride ions in the compound, the chemical formula will represent the simplest ratio of cations and anions.
We are told in the question that sodium ions have a charge of one plus and chloride ions have a charge of one minus. We can see that one positively charged sodium cation and one negatively charged chloride anion would form a neutral compound. As the three-dimensional network builds so long as the ratio of sodium ions to chloride ions is one to one, the compound will remain neutral. We can write the chemical formula NaCl for this compound, indicating that the ratio of sodium cations to chloride anions is one to one. By convention, we write the cation term first in the chemical formula.
So, the formula of the compound formed from sodium ions and chloride ions is NaCl.
