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Chemistry is all around you. It’s in the air you breathe, the feelings you experience, the food you eat, and, yes, the bubbles in your drinks. And in this course, you’re going to take a look under the hood of everyday life to find out about the chemistry that makes it all possible. These lectures will include a variety of demonstrations, some of which you can try at home. This lecture explores the bubbles in soft drinks as way to demonstrate some basic concepts that you’ll need for the rest of the course. Soft drinks are simple examples of mixtures. In chemistry, a mixture is the combination of two or more different substances that are physically blended but chemically unchanged. In this case, carbon dioxide gas has been injected into flavored liquid through the process of carbonation. When looking at a glass of soda, you can see that the carbon dioxide has stayed in its gas form. It tries to escape through little bubbles that float up to the surface. And when a glass of soda is left alone for a while, eventually most of the gas escapes, and the drink goes flat. That tells you that carbon dioxide and water don’t mix well, and when they do, the result isn’t very stable. But why is that? To understand why soft drinks are bubbly, consider the two molecules that make up more than 90% of a soda: water and carbon dioxide. Water is made up of 2 hydrogen atoms and 1 oxygen atom. Carbon dioxide has 2 oxygen atoms bonded to a single carbon atom. Every atom is made up of three basic particles: protons, neutrons, and electrons. Positively charged protons and uncharged neutrons sit together at the center of the atom in the nucleus. Orbiting the nucleus are the negatively charged electrons. Chemists categorize atoms as different elements depending on how many protons they have. The periodic table—the official list of all the known elements in the universe—is organized in ascending number of protons. In a normal state, an atom has an equal number of electrons orbiting around the nucleus that balance out the charge. Hydrogen is the first and the simplest atom; in its normal state, it has 1 proton and 1 electron. Element number 6, carbon, has 6 of each, and oxygen has 8 of each. Protons and a variable number of neutrons sit together in the nucleus as the atom gets heavier. But the electrons live in layers, called shells, around the nucleus.