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Like barium and the alkali metals, radium crystallizes in the body-centered cubic structure at standard temperature and pressure: the radium–radium bond distance is 514.8 picometers. [8] Radium has a density of 5.5 g/cm 3, higher than that of barium, and the two elements have similar crystal structures (bcc at standard temperature and pressure).
It is one of the densest gases at room temperature (a few are denser, e.g. CF 3 (CF 2) 2 CF 3 and WF 6) and is the densest of the noble gases. Although colorless at standard temperature and pressure, when cooled below its freezing point of 202 K (−71 °C; −96 °F), it emits a brilliant radioluminescence that turns from yellow to orange-red ...
88 Ra radium; use: 973 K: 700 °C: 1292 °F WEL: ... unless noted. Triple point temperature values (marked "tp") are not valid at standard pressure. ... The bcc phase ...
The longest half-lives among them are 1.387 million years for beryllium-10, 99.4 thousand years for calcium-41, 1599 years for radium-226 (radium's longest-lived isotope), 28.90 years for strontium-90, 10.51 years for barium-133, and 5.75 years for radium-228. All others have half-lives of less than half a year, most significantly shorter.
The following table gives the crystalline structure of the most thermodynamically stable form(s) for elements that are solid at standard temperature and pressure. Each element is shaded by a color representing its respective Bravais lattice, except that all orthorhombic lattices are grouped together.
The noble gases—including helium—can form stable molecular ions in the gas phase. The simplest is the helium hydride molecular ion , HeH + , discovered in 1925. [ 59 ] Because it is composed of the two most abundant elements in the universe, hydrogen and helium, it was believed to occur naturally in the interstellar medium , and it was ...
Radium: Actinium: Thorium: ... theoretical studies predict that it would be a solid at room temperature, ... If the two nuclei can stay close past that phase ...
This reaction raises the temperature to about 2000 °C. The carbon monoxide reduces the iron ore to metallic iron: [119] Fe 2 O 3 + 3 CO → 2 Fe + 3 CO 2. Some iron in the high-temperature lower region of the furnace reacts directly with the coke: [119] 2 Fe 2 O 3 + 3 C → 4 Fe + 3 CO 2