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Astatine is a chemical element; it has symbol At and atomic number 85. It is the rarest naturally occurring element in the Earth's crust, occurring only as the decay product of various heavier elements. All of astatine's isotopes are short-lived; the most stable is astatine-210, with a half-life of 8.1 hours.
Astatine-212 and astatine-216 are expected to decay either way. The most stable isotope of astatine is astatine-210, which has a half-life of about 8.1 hours. This isotope's primary decay mode is positron emission to the relatively long-lived alpha emitter, polonium-210. In total, only five isotopes of astatine have half-lives exceeding one ...
The specific heat of the human body calculated from the measured values of individual tissues is 2.98 kJ · kg−1 · °C−1. This is 17% lower than the earlier wider used one based on non measured values of 3.47 kJ · kg−1· °C−1.
The temperature of a system in thermal equilibrium is the same as the temperature of any part of it, so temperature is an intensive quantity. If the system is divided by a wall that is permeable to heat or to matter, the temperature of each subsystem is identical. Additionally, the boiling temperature of a substance is an intensive property.
[1] ClF 3 is the most reactive of the XY 3 interhalogens. ICl 3 is the least reactive. BrF 3 has the highest thermal stability of the interhalogens with four atoms. ICl 3 has the lowest. Chlorine trifluoride has a boiling point of −12 °C. Bromine trifluoride has a boiling point of 127 °C and is a liquid at room temperature. Iodine ...
Chain-melted state: Metals, such as potassium, at high temperature and pressure, present properties of both a solid and liquid. Wigner crystal : a crystalline phase of low-density electrons. Hexatic state , a state of matter that is between the solid and the isotropic liquid phases in two dimensional systems of particles.
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The standard state for liquids and solids is simply the state of the pure substance subjected to a total pressure of 10 5 Pa (or 1 bar). For most elements, the reference point of Δ f H ⦵ = 0 is defined for the most stable allotrope of the element, such as graphite in the case of carbon , and the β-phase ( white tin ) in the case of tin .