Period 6 element living organism. Tungsten interferes with molybdenum and copper metabolism, and is somewhat toxic to animal life. Rhenium is a chemical element with the symbol Re and atomic number 75. It is a silvery-white, heavy, third-row transition metal in group 7 of the periodic table. With an "estimated" average concentration of 1 part per billion (ppb), rhenium is one of the rarest elements in the Earth's crust. The free element has the third-highest melting point and highest boiling point of any element. Rhenium resembles manganese chemically and is obtained as a by-product of molybdenum and copper ore's extraction and refinement. Rhenium
Melting point the same space. The Lindemann criterion states that melting is expected when the vibration root mean square amplitude exceeds a threshold value. Assuming that all atoms in a crystal vibrate with the same frequency "ν", the average thermal energy can be estimated using the equipartition theorem as where "m" is the atomic mass, "ν" is the frequency, "u" is the average vibration amplitude, "k" is the Boltzmann constant, and "T" is the absolute temperature. If the threshold value of "u" is "ca" where "c" is the Lindemann constant and "a" is the atomic spacing, then the melting point is estimated