What Does the Structure of an Atom Look Like?

Although atoms cannot be divided without altering their chemical nature, they have subatomic structures. The structure of an atom is composed of three types of particles that are differently charged. Investigation into atomic structure is a relatively recent field, but knowledge of the atom itself dates back to ancient India and Greece.

History

Ancient Indian schools originated atomic theory in the sixth century B.C.E. The term "atom" comes from ancient Greek philosophy. The Greek atomists theorized that atoms were the essential building blocks of all reality and could not be broken down any further. It was not until the early twentieth century that physicists built upon earlier particle theory and discovered that atoms have differing properties. This led to the discovery of isotopes, atoms that belong to the same element but which differ. Meanwhile, Einstein and other physicists experimented with atomic mass and dimensions. The history of the structure of the atom is not a closed text. Because of the discovery of subatomic particles, physics has entered a realm that penetrates more deeply into material reality and extends beyond the reaches of the known universe than Sir Isaac Newton could have imagined.

Significance

The discovery of and investigation into the structure of atoms has far-reaching implications. Human beings will forever investigate, as deeply as possible, the nature and substance of the world. At a purely material level, atomic energy was one of the significant discoveries of the twentieth century and continues to be explored and debated. Additionally, quantum physicists have theorized about subatomic particles in ways that challenge so-called common sense understanding of the nature of reality. For example, in simple terms, theories about the particle and wave-like properties of a subatomic particle have spawned philosophical investigation into the nature of knowing and how human perception interrelates with the sensory world.

Function

Because of their opposite charges, protons and electrons stay close together, with the electron in constant motion, creating a cloudlike environment around the nucleus. Although electrons are particles, they have wavelike properties. This means that electrons are less like small specks and more like light beams. Neutrons, neutrally charged, serve as balance for atoms with uneven electrical charges. For example, helium has two protons and two neutrons, which keep the nucleus together by matching the number of protons.

Features

Atoms are nearly completely empty space. Subatomic particles, neutrons, electrons and protons form the structure of an atom. Each subatomic particle has unique properties. Neutrons are heavy and have no electrical charge. Electrons are very small and very light. They have a negative (-) charge. Protons are significantly larger than electrons, heavy like neutrons and have a positive (+) charge. Protons are in the nucleus. Every atom has some combination of these particles. The simplest atom, hydrogen, has one proton and one electron. Atomic numbers and atomic mass are the ways to define a particular atom's structure. Hydrogen has an atomic number of 1 (number of protons) and an atomic mass of 1 (number of protons plus neutrons).

Identification

Physicists use increasingly sophisticated means to identify the properties of subatomic particles. Using a scanning tunnel microscope, physicists view the atomic structure of surfaces. Other methods of identifying the structure and properties of atoms include ionizing (removing an electron) with a mass spectrometer, which can measure different ion beams. Other methods are vaporizing with different spectrometers and measurement of atomic energy loss. Helium was discovered in the light wavelength of the sun before helium was discovered on earth. Analysis continues into certain light wavelengths from stars.

Resources

• Department of Sciences, John Jay College: Atomic Structure
• MathMol Hypermedia Textbook: Structure of the Atom
• Georgia Perimeter College: Atoms