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Number density. The number density (symbol: n or ρN) is an intensive quantity used to describe the degree of concentration of countable objects (particles, molecules, phonons, cells, galaxies, etc.) in physical space: three-dimensional volumetric number density, two-dimensional areal number density, or one-dimensional linear number density.
Hydrogen is a chemical element; it has symbol H and atomic number 1. It is the lightest element and, at standard conditions, is a gas of diatomic molecules with the formula H2, sometimes called dihydrogen, [11] but more commonly called hydrogen gas, molecular hydrogen or simply hydrogen. It is colorless, odorless, [12] non-toxic, and highly ...
A hydrogen atom is an atom of the chemical element hydrogen. The electrically neutral hydrogen atom contains a nucleus of a single positively charged proton and a single negatively charged electron bound to the nucleus by the Coulomb force. Atomic hydrogen constitutes about 75% of the baryonic mass of the universe. [1]
Nuclear density is the density of the nucleus of an atom. For heavy nuclei, it is close to the nuclear saturation density nucleons / fm 3, which minimizes the energy density of an infinite nuclear matter. [1] The nuclear saturation mass density is thus kg/m 3, where mu is the atomic mass constant. The descriptive term nuclear density is also ...
The atomic number or nuclear charge number (symbol Z) of a chemical element is the charge number of its atomic nucleus. For ordinary nuclei composed of protons and neutrons, this is equal to the proton number (np) or the number of protons found in the nucleus of every atom of that element. The atomic number can be used to uniquely identify ...
New York: The International Nickel Company, Inc., 1941: 16. — "Values ranging from 21.3 to 21.5 gm/cm 3 at 20 °C have been reported for the density of annealed platinum; the best value being about 21.45 gm/cm 3 at 20 °C." 21.46 g/cm 3 — Rose, T. Kirke. The Precious Metals, Comprising Gold, Silver and Platinum.
Nitrogen. hexagonal (hP4) Nitrogen is a chemical element; it has symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at seventh in total abundance in the Milky Way and the Solar System.
The Bohr radius ( ) is a physical constant, approximately equal to the most probable distance between the nucleus and the electron in a hydrogen atom in its ground state. It is named after Niels Bohr, due to its role in the Bohr model of an atom. Its value is 5.291 772 105 44(82) × 10−11 m. [1][2]