Compressibility (also known as the coefficient of compressibility is a measure of the relative volume change of a fluid or solid as a response to a pressure (or mean stress) change. Increasing the pressure on an material (especially for liquids or gases) decreases the volume of the object and thus increases its density via the atomic number density. This dependence is usually expressed by the coefficient of linear or volume expansion. This effect is caused by a decrease in the atomic number density. As a result of this expansion, the density of most materials decreases. Rising temperatures make the liquid expand in a liquid-in-tube thermometer and bend bimetallic strips. Most materials expand when their temperatures increase. This variation is typically small for solids and liquids but much greater for gases. The density of a material varies with temperature and pressure. The density of Hassium results from its high atomic weight and from the significant decrease in ionic radii of the elements in the lanthanide series, known as lanthanide and actinide contraction. It has an estimated density of 40.7 x 10 3 kg/m 3. The most stable known isotope, 269Hs, has a half-life of approximately 9.7 seconds. It is a synthetic element (first synthesised at Hasse in Germany) and radioactive. Hassium is a chemical element with symbol Hs and atomic number 108. If we include man made elements, the densest so far is Hassium. The densest material found on earth is the metal osmium, but its density pales by comparison to the densities of exotic astronomical objects such as white dwarf stars and neutron stars. Since nucleons ( protons and neutrons) make up most of the mass of ordinary atoms, the density of normal matter tends to be limited by how closely we can pack these nucleons and depends on the internal atomic structure of a substance. The atomic number density (N atoms/cm 3) of a pure material having atomic or molecular weight (M grams/mol) and the material density (⍴ gram/cm 3) is easily computed from the following equation using Avogadro’s number ( N A = 6.022×10 23 atoms or molecules per mole): The atomic number density (N atoms/cm 3), which is associated with atomic radii, is the number of atoms of a given type per unit volume (V cm 3) of the material. Therefore it is determined by the mass number (number of protons and neutrons). The atomic mass is carried by the atomic nucleus, which occupies only about 10 -12 of the total volume of the atom or less, but it contains all the positive charge and at least 99.95% of the total mass of the atom. Since the density (ρ) of a substance is the total mass (m) of that substance divided by the total volume (V) occupied by that substance, it is obvious, the density of a substance strongly depends on its atomic mass and also on the atomic number density (N atoms/cm 3), Density – Atomic Mass and Atomic Number Density The Standard English unit is pounds mass per cubic foot ( lbm/ft 3). The standard SI unit is kilograms per cubic meter ( kg/m 3). In words, the density (ρ) of a substance is the total mass (m) of that substance divided by the total volume (V) occupied by that substance.
It is an intensive property, which is mathematically defined as mass divided by volume: Typical densities of various substances are at atmospheric pressure.ĭensity is defined as the mass per unit volume.
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