Atom | Definition, Structure, History, Examples, Diagram, & Facts ...
网页4 天之前 · 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 …
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.
Atom - Development, Theory, Structure | Britannica
网页4 天之前 · 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 model | Definition, History, Development, Examples,
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 …
Atom - Electrons, Orbitals, Energy | Britannica
网页4 天之前 · The next most-complex atom is helium, which has two protons in its nucleus and two orbiting electrons. These electrons fill the two available states in the lowest shell, producing what is called a filled shell. The next atom is lithium, with three electrons.
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 …
Periodic table | Definition, Elements, Groups, Charges, Trends,
网页2024年9月20日 · periodic table, in chemistry, the organized array of all the chemical elements in order of increasing atomic number —i.e., the total number of protons in the atomic nucleus.
atom - Students | Britannica Kids | Homework Help
网页Atoms are made up of three basic types of particle: protons, neutrons, and electrons. These particles (as well as other particles smaller than atoms) are known as subatomic particles. Two of the three types of basic particle in an atom are electrically charged.
Atomic theory | Definition, Scientists, History, & Facts | Britannica
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.