The Statue of Liberty, pictured above, is an icon of America and freedom. The statue is made of steel and covered with a thin layer of copper, the same type of matter that pennies are made of. Copper is a brownish red metal, so why is the statue green? Chemistry, which is a branch of physical science, has the answer.
What Is Chemistry?
Chemistry is the study of matter and energy and how they interact, mainly at the level of atoms and molecules. Basic concepts in chemistry include chemicals, which are specific types of matter, and chemical reactions. In a chemical reaction, atoms or molecules of certain types of matter combine chemically to form other types of matter. All chemical reactions involve energy.
Q: How do you think chemistry explains why the copper on the Statue of Liberty is green instead of brownish red?
A: The copper has become tarnished. The tarnish—also called patina—is a compound called copper carbonate, which is green. Copper carbonate forms when copper undergoes a chemical reaction with carbon dioxide in moist air. The green patina that forms on copper actually preserves the underlying metal. That’s why it’s not removed from the statue. Some people also think that the patina looks attractive.
Chemistry and You
Chemistry can help you understand the world around you. Everything you touch, taste, or smell is made of chemicals, and chemical reactions underlie many common changes. For example, chemistry explains how food cooks, why laundry detergent cleans your clothes, and why antacid tablets relieve an upset stomach. Other examples are illustrated in the figure below. Chemistry even explains you! Your body is made of chemicals, and chemical changes constantly take place within it.
Each of these pictures represents a way that chemicals and chemical reactions affect our lives.
Summary
- Chemistry is the study of matter and energy and how they interact, mainly at the level of atoms and molecules. Basic concepts in chemistry include chemicals and chemical reactions.
- Chemistry can help you understand the world around you. Everything you touch, taste, or smell is a chemical, and chemical reactions underlie many common changes.