Download Understanding Chemical Formulas: Empirical vs. Molecular and Structural Representations and more Study notes Chemistry in PDF only on Docsity! What is a Chemical Formula? We encounter chemical substances and compounds every day.The substances under the kitchen sink that we use to clean our houses as well as those that are staples in our medicine cabinet are made up of chemical substances. These chemicals are made up of a fixed proportion of atoms, and these atoms are arranged in a certain way. In order to figure out what these proportions are and how they are arranged for any given substance, we need to know the chemical formula of the substance or compound. A compound is a substance made up of a definite proportion of two or more elements. A chemical formula tells us the number of atoms of each element in a compound. It contains the symbols of the atoms of the elements present in the compound as well as how many there are for each element in the form of subscripts. Each chemical substance has a specific chemical composition, so these chemical substances have their own chemical formula. Let's take a look at the chemical formula of sucrose: there are 12 carbon (C) atoms, 22 hydrogen (H) atoms and 11 oxygen (O) atoms. If we look at butane, we see it has 4 carbon (C) atoms and 10 hydrogen (H) atoms. Empirical Formula The word empirical is defined as something that is verified by observation. In chemistry, we verify facts by performing experiments. So, the empirical formula is defined as the simplest ratio of whole numbers of elements that make up a compound, and this type of formula is derived from experimental data. Just like how we simplify fractions in math class, in chemistry we can simplify formulas as well. In this case, let's look at the molecular formula of glucose: While the molecular formula gives us the actual number of atoms of each element in a molecule, the empirical formula gives us the simplest ratio and not the actual number of atoms of an element. Here are some examples of empirical formulas derived from molecular formulas: Sometimes, there are molecular formulas that are already at their simplest ratio which means they cannot be further reduced. In these cases, the molecular formula is the same as the empirical formula which can be seen with these examples.
