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 modern physics.

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 …

Dec 11, 2024 · The single most important characteristic of an atom is its atomic number (usually denoted by the letter Z), which is defined as the number of units of positive charge (protons) in the nucleus. For example, if an atom has a Z of 6, it is carbon, while a Z …

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 …

Transuranium element, any of the chemical elements that lie beyond uranium in the periodic table—i.e., those with atomic numbers greater than 92. Twenty-six of these elements have been discovered and named or are awaiting confirmation of their discovery.

atomic physics, Scientific study of the structure of the atom, its energy states, and its interaction with other particles and fields. The modern understanding of the atom is that it consists of a heavy nucleus of positive charge surrounded by a cloud of light, negatively charged electrons.

Modern atomism arose with the flowering of science in the present sense of the word. The 17th century. In the history of atomism the 17th century occupies a special place for two reasons: it saw the revival of Democritean atomism, and it saw the beginning of a scientific atomic theory.

Dec 11, 2024 · The emergence of experimental science; The beginnings of modern atomic theory. Experimental foundation of atomic chemistry; Atomic weights and the periodic table; Kinetic theory of gases; Studies of the properties of atoms. Size of atoms; Electric properties of atoms; Light and spectral lines; Discovery of electrons; Identification of positive ions

Atomic mass, the quantity of matter contained in an atom of an element. It is expressed as a multiple of one-twelfth the mass of the carbon-12 atom, which is assigned an atomic mass of 12 units. In this scale, 1 atomic mass unit (amu) corresponds to 1.66 x 10^−24 gram.

Jan 17, 2025 · atomic number, the number of a chemical element in the periodic system and on the periodic table that equals the number of protons in the nucleus of the atom. The elements are arranged on the table in order of increasing number of protons in the nucleus.