Atom definition in science
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Scientific Definition of an Atom
An atom is the basic unit of matter, made up of a central nucleus containing protons and neutrons, surrounded by electrons that orbit the nucleus. The nucleus is held together by the strong nuclear force, while the electrons are bound to the nucleus by electromagnetic forces. The arrangement of electrons in quantized orbits gives the atom its size and prevents atoms from overlapping, making them behave like hard spheres in many models .
Historical Evolution of the Atom Concept
The idea that matter is made of atoms dates back to ancient Greek philosophers, but it was not until the 19th century that experiments in chemistry and physics provided strong evidence for atoms. Early definitions described atoms as indivisible particles that make up all matter, occupy space, and have mass. However, discoveries in the 20th century, such as the structure of the nucleus and the existence of subatomic particles, showed that atoms themselves are made of smaller components 34.
Modern Understanding and Terminology
Today, the term "atom" refers specifically to the smallest unit of a chemical element that retains its chemical properties. Atoms are not indivisible, as once thought, but are composed of protons, neutrons, and electrons. The term "elementary particle" is now used for truly indivisible particles like electrons and quarks, while "atom" remains the standard term for the chemical building blocks of matter 256.
Atoms in Science Education
The current definitions of atom, molecule, element, and compound are considered both philosophically sound and effective for teaching. An atom is defined as the smallest unit of an element that can exist either alone or in combination with other atoms, forming molecules and compounds .
Conclusion
In science, an atom is the smallest unit of a chemical element, consisting of a nucleus of protons and neutrons, with electrons in orbit around it. While the concept has evolved over time, the atom remains a fundamental building block in our understanding of matter and chemistry 13456.
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