Ask a Chemistry Student: What is Energy?

An alum from the class of 2010 emailed us about a month ago and told us he ran a Williams science publication (coincidentally also called the ScientEphic!) when he was a student here. We took a look at some of their old publications and enjoyed their section called “Ask A Science Major.” So The ScientEphic is beginning a series based on that section. We asked students from four departments – chemistry, physics, biology, and astronomy – to explain the concept of energy. We’ll publish their responses over the next four days.

The question, “What is energy?” might seem too broad to some people or too obvious to others. But the truth of the matter is that although all science classes discuss energy in some way or another, it’s difficult to come up with a concise, easy-to-conceptualize answer. In the following short responses, science students grapple with the question, exploring the concept of energy in relation to their area of study.

Ask a Science Student, Part 1: Chemistry

By Matt Davies ’17

Chemically speaking, energy is a system’s potential for reaction. Electron-exchanging reactions take place because molecules prefer to be in the lowest possible energy state. With this understanding of energy, scientists have been able to model the reactions that led to life on earth. Earth’s early atmosphere consisted largely of carbon dioxide, hydrogen, ammonia, and water vapor. In that atmosphere, with the addition of energy from lightning, some of these gas molecules have lower energy when they exist in the form of simple amino acids such as glycine. These amino acids are the essential building blocks of life.

Nowadays, feeding a huge population poses an incredible problem, as growing enough food requires amounts of nutrients that don’t exist naturally in the world. Though we are swimming in nitrogen gas, plants can’t utilize it for nutrition, as the bonds between nitrogen require too much energy to break. To solve this issue, scientists have developed the Haber Process, in which atmospheric nitrogen is converted into bio-available ammonia. The energy used to accomplish this process comes from the breaking of bonds in methane, a natural gas formed by the decomposition of ancient plants deep in the earth’s crust. The process is accomplished by changing the heat and pressure of the system—its available energy—to force nitrogen gas and hydrogen into a new molecule, ammonia. Thus, plants are fed by the energy of plants, and in turn they feed us and sustain about one third of the earth’s population.

A molecule’s potential for reaction, its potential energy, gives it utility in our everyday world. However, energy can be just as important in preventing compounds from reacting. Just think if the materials in our cars were highly reactive – surely one doesn’t want a tire to change composition and degrade while driving on the highway. Polymers like styrene-butadiene – the rubber car tires are made of – are selected for their ability to stay as they are for many years. This property is a result of the high amount of energy needed to break these molecules’ bonds.

Ultimately, our understanding of energy allows us to live the way we do, by manipulating and controlling our environment.

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