Heat, atomic specific

Temperature Range, 0 C. Mean Specific Heat. Temperature, °C. Specific Heat. Atomic Heat. 

When energy is supplied to a solid this may result in an increase in the vibrations of the electrons, ions, atoms or molecules of the sample. In a sample containing moving electrons this will lead to a strong heat conduction. Most ceramics do not conduct heat. The specific heat strongly depends on the porosity of the material. 

Formerly these metallic properties were attributed to the presence of free electrons. The classical theory of this electron gas (Lorentz) leads, however, to absurdities for instance, a specific heat of 3/2 R had to be expected for this monatomic gas, contrary to the experience that Dulong and Petit s rule (atomic specific heat 6/2 R) holds for both conductors and non-conductors. The calculated ratio of heat conductivity to electrical conductivity (Wiedemann-Franz constant) also did not agree with observation. 

Up to now, our equations have been continuum-level descriptions of mass flow. As with the other transport properties discussed in this chapter, however, the primary objective here is to examine the microscopic, or atomistic, descriptions, a topic that is now taken up. The transport of matter through a solid is a good example of a phenomenon mediated by point defects. Diffusion is the result of a concentration gradient of solute atoms, vacancies (unoccupied lattice, or solvent atom, sites), or interstitials (atoms residing between lattice sites). An equilibrium concentration of vacancies and interstitials are introduced into a lattice by thermal vibrations, for it is known from the theory of specific heat, atoms in a crystal oscillate around their equilibrium positions. Nonequilibrium concentrations can be introduced by materials processing (e.g. rapid quenching or irradiation treatment). 

Element. Specific Heat. Atomic Weight. Product. 

Specific heat and chemical character. In 1819 Dulong and Petit discovered the following law The product of the atomic weight and the specific heat is a constant, namely 6 4, for all elements in the solid state. The atoms of the elements have all, therefore, the same specific heat (atomic heat). The following table shows that this law only holds approximately, and that several of the elements are exceptions to it, if we take the specific heat at the ordinary temperature as the basis of our calculations. The values of c are taken from the third edition of Landolt and Bornstein. The values of the true specific heat at room temperature were taken wherever possible. When Wied. Ann. 66, 235 (1898). 

Atomic Absorption Spectrometry (AAS) is a quantitative spectroscopic method based on the ability of free atoms, produced in an appropriate medium, like a flame, plasma, or a heated graphite tube, to absorb radiation of an atom-specific wavelengfh. 

The specific heat of crystals is dependent on the vibration specific heat of the ions, the electron specific heat, the specific heat due to diffusion of atoms, the specific heat due to defect formation, etc. In particular, the electron specific heat is proportional to the temperature the specific heat due to diffusion and self-diffusion is an exponential function of the temperature. 

A = magnetic cluster specific heat C = specific heat H = magnetic field strength kg = Boltzmann s constant L(jc) = Langevin function M = magnetization (M) = average atomic weight... 

ATOMIC SPECIFIC HEATS BETWEEN THE BOILING POINTS OF LIQUID NITROGEN AND HYDROGEN. I. THE MEAN ATOMIC SPECIFIC HEATS AT 50 DEGREES ABSOLUTE OF THE ELEMENTS A PERIODIC FUNCTION OF THE ATOMIC WEIGHTS. 

Element Specific heat Atomic weight 0= i Product of atomic weight and specific heat... 

Semiempirical Organic molecules. Several Atomistic structures, heats of Atom-specific parameters, well... 

Following the discovery in 1912 by William Heruy Bragg and his son William Lawrence Bragg that x-rays were diffracted by crystals, Debye reported that the thermal vibrations of the atoms in crystals affected the x-ray patterns. Based on his work on heat capacities (specific heats), he determined the temperature dependence of the intensity of the diffraction pattern. This led him to consider the x-ray diffraction of randomly oriented molecules. 

In 1819, DULONG and PETIT [1.1] published the results of their specific heat measurements of thirteen solid elements at room temperature. From these measurements, they deduced that the product of the specific heat and the atomic weight was approximately a constant C = 3R = 5.96 cal mole K . BOLTZMANN in 1871 demonstrated that the law of Dulong and Petit follows from his equi-partition principle. However, in 1875, WEBER [1.2] found that the atomic specific heat of silicon, boron and carbon are considerably lower than the Dulong-Petit value. For example, the atomic specific heat of silicon, boron and diamond were found to be 4.8, 2.7, and 1.8 cal mole K", respectively, at room temperature. Subsequent specific heat measurements at T < 300 K revealed that the specific heat of solids decreased rapidly with decreasing temperature. Classical theory does not explain this behaviour. 

In statistical mechanics (e.g. the theory of specific heats of gases) a degree of freedom means an independent mode of absorbing energy by movement of atoms. Thus a mon-... 

Dulong and Pedt s law The product of the atomic weight and the specific heat of a metal is constant of value approximately 6-2. Although not true for all metals at ordinary temperatures, these metals and several non-metals approximate to the law at high temperatures. 

The expansion coefficient of a solid can be estimated with the aid of an approximate thermodynamic equation of state for solids which equates the thermal expansion coefficient with the quantity where yis the Griineisen dimensionless ratio, C, is the specific heat of the solid, p is the density of the material, and B is the bulk modulus. For fee metals the average value of the Griineisen constant is near 2.3. However, there is a tendency for this constant to increase with atomic number. 

A poly(tribromostyrene) with the bromine atoms attached to the benzene ring is marketed by the Ferro corporation as F yro-Chek 68 PB as a heat-resisting fire retardant used in conjunction with antimony oxide. The polymer has an exceptionally high specific gravity, reputedly of 2.8, and a softening point of 220°C. 

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