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Parts-per-million cube of relative abundance by mass of elements in an average adult human body down to 1 ppm. About 99% of the mass of the human body is made up of six elements: oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus. Only about 0.85% is composed of another five elements: potassium, sulfur, sodium, chlorine, and magnesium ...
These five elements have a strong affinity for sulfur; in the human body they usually bind, via thiol groups (–SH), to enzymes responsible for controlling the speed of metabolic reactions. The resulting sulfur-metal bonds inhibit the proper functioning of the enzymes involved; human health deteriorates, sometimes fatally. [ 56 ]
Trace metals within the human body include iron, lithium, zinc, copper, chromium, nickel, cobalt, vanadium, molybdenum, manganese and others. [ 1 ] [ 2 ] [ 3 ] Some of the trace metals are needed by living organisms to function properly and are depleted through the expenditure of energy by various metabolic processes of living organisms.
The heaviest element known at the end of the 19th century was uranium, with an atomic mass of about 240 (now known to be 238) amu. Accordingly, it was placed in the last row of the periodic table; this fueled speculation about the possible existence of elements heavier than uranium and why A = 240 seemed to be the limit.
Its prevalence in the human body—at an adult average of 120 mg [t] —is nevertheless exceeded only by zinc (2500 mg) and iron (4000 mg) among the heavy metals. [259] Lead salts are very efficiently absorbed by the body. [260] A small amount of lead (1%) is stored in bones; the rest is excreted in urine and feces within a few weeks of exposure.
Period 4 includes the biologically essential elements potassium and calcium, and is the first period in the d-block with the lighter transition metals. These include iron, the heaviest element forged in main-sequence stars and a principal component of the Earth, as well as other important metals such as cobalt, nickel, and copper. Almost all ...
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Uranium, element 92, is the heaviest element to occur in significant quantities in nature; heavier elements can only be practically produced by synthesis. The first synthesis of a new element— neptunium , element 93—was achieved in 1940 by a team of researchers in the United States. [ 57 ]