What is an Atom?

Atoms are the building blocks of matter. All matter on Earth — solids, liquids and gases — is composed of atoms. Scientists have long been curious about the structure and behavior of atoms, which are too small to be seen with the naked eye. In the last 150 years, research has yielded great insight into the structure and properties of atoms, allowing us to better understand the fundamental workings of Nature.

Atomic Structure

An atom is composed of a small, dense nucleus surrounded by an electron cloud. The nucleus is composed of positively charged protons and neutral neutrons. The electron cloud is composed of negatively charged electrons. The number of protons in an atom determines what element it is. The number of neutrons can vary, however, leading to isotopes of the same element with different masses.

The electron cloud — or energy levels — gives atoms their chemical properties. The electrons occupy distinct shells or orbits of different energy levels, which can absorb or emit energy. These processes give rise to many of the chemical reactions that occur in Nature and make various substances interact with one another.

Modern Trends and Theory

Modern advances in physics have helped us gain further insight into the behavior and nature of atoms. Quantum mechanics, for example, has revealed many of the bizarre properties of atoms, and atomic energy has been used to power nuclear reactors. Scientists have even come up with ways to manipulate particles at the atomic level to build new materials and create novel technologies.

All these advances have allowed us to better understand the fundamental behavior of atoms and the materials they build up. In the near future, scientists expect to continue to make great strides in our understanding of atoms with continued research and advances in technology.