Chemists study interactions and reactions of atoms and molecules. They design experiments to discover how and why reactions occur by understanding the properties of matter.
WHY STUDY ATOMS AND MOLECULES?
Think about this: A plant growing, a cell dividing, a thought floating through your head and a muscle contraction are just a few examples from the living world (biology) that are essentially molecular phenomena. All of these processes involve the interaction of energy and molecules and matter.
Everything else we see in the non-living world is made up of the different types of atoms or elements. Look at your computer or phone— the screen, the housing, the electronics, the mechanism for sending and receiving data etc. — are all are made using materials whose properties may be understood by studying chemistry. Indeed, many of the objects and products we use every day are made from materials invented by chemists. Chemistry is fundamental for understanding the world around us.