Atom | Definition, Structure, History, Examples, Diagram, & Facts
网页2024年8月17日 · All atoms are roughly the same size, whether they have 3 or 90 electrons. Approximately 50 million atoms of solid matter lined up in a row would measure 1 cm (0.4 inch). A convenient unit of length for measuring atomic sizes is …
Basic concept and structure of an atom | Britannica
网页atom, Smallest unit into which matter can be divided and still retain the characteristic properties of an element. The word derives from the Greek atomos (“indivisible”), and the atom was believed to be indivisible until the early 20th century, when electrons and the nucleus were discovered.
Atom - Development, Theory, Structure | Britannica
网页2024年8月17日 · Studies of the properties of atoms. Size of atoms; Electric properties of atoms; Light and spectral lines; Discovery of electrons; Identification of positive ions; Discovery of radioactivity; Models of atomic structure. Rutherford’s nuclear model; Moseley’s X-ray studies; Bohr’s shell model; The laws of quantum mechanics; Schrödinger’s ...
Atomic physics | Structure, Particles & Energy | Britannica
网页Atomic physics, the scientific study of the structure of the atom, its energy states, and its interactions with other particles and with electric and magnetic fields. Atomic physics has proved to be a spectacularly successful application of quantum mechanics, which is one of the cornerstones of.
Atomic model | Definition, History, Development, Examples, & Facts
网页atomic model, in physics, a model used to describe the structure and makeup of an atom. Atomic models have gone through many changes over time, evolving as necessary to fit experimental data. For a more in-depth discussion of the history of atomic models, see atom: development of atomic theory.
atom - Kids | Britannica Kids | Homework Help
网页The tiny particles called atoms are the basic building blocks of all matter. Atoms can be combined with other atoms to form molecules, but they cannot be divided into smaller parts by ordinary means. The word atom comes from …
Molecule | Definition, Examples, Structures, & Facts | Britannica
网页2024年9月13日 · Molecule, a group of two or more atoms that form the smallest identifiable unit into which a pure substance can be divided and still retain the composition and chemical properties of that substance. Learn more about the properties and structures of …
Atomism | Definition, Philosophy, History, & Facts | Britannica
网页Atomism, any doctrine that explains complex phenomena in terms of aggregates of fixed particles or units. This philosophy has found its most successful application in natural science: according to the atomistic view, the material universe is composed of minute particles, which are considered to be.
Atom - Nuclear Model, Rutherford, Particles | Britannica
网页2024年8月17日 · Many physicists distrusted the Rutherford atomic model because it was difficult to reconcile with the chemical behaviour of atoms. The model suggested that the charge on the nucleus was the most important characteristic of the …
Atomic theory | Definition, Scientists, History, & Facts
网页Atomic theory, ancient philosophical speculation that all things can be accounted for by innumerable combinations of hard, small, indivisible particles (called atoms) of various sizes but of the same basic material; or the modern scientific theory of matter according to which the chemical elements.