Heavy metals

heavy metalheavy elementsheavy elementheavy-metalheavymetalsheavier than ironheavy metal ionheavy metal ionshigh-Z
Heavy metals are generally defined as metals with relatively high densities, atomic weights, or atomic numbers.wikipedia
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Mercury (element)

mercuryquicksilverHg
The definitions surveyed in this article encompass up to 96 out of the 118 known chemical elements; only mercury, lead and bismuth meet all of them.
A heavy, silvery d-block element, mercury is the only metallic element that is liquid at standard conditions for temperature and pressure; the only other element that is liquid under these conditions is the halogen bromine, though metals such as caesium, gallium, and rubidium melt just above room temperature.

Lead

Pblead orelead mining
The definitions surveyed in this article encompass up to 96 out of the 118 known chemical elements; only mercury, lead and bismuth meet all of them.
It is a heavy metal that is denser than most common materials.

Platinum

Ptcompounds of platinumdouble Platinum
The earliest known metals—common metals such as iron, copper, and tin, and precious metals such as silver, gold, and platinum—are heavy metals.
Being a heavy metal, it leads to health problems upon exposure to its salts; but due to its corrosion resistance, metallic platinum has not been linked to adverse health effects.

Chemical element

elementelementschemical elements
The definitions surveyed in this article encompass up to 96 out of the 118 known chemical elements; only mercury, lead and bismuth meet all of them.
Some of these elements, notably bismuth (atomic number 83), thorium (atomic number 90), and uranium (atomic number 92), have one or more isotopes with half-lives long enough to survive as remnants of the explosive stellar nucleosynthesis that produced the heavy metals before the formation of our Solar System.

Metal

metalsmetal ionsmetal ion
Heavy metals are generally defined as metals with relatively high densities, atomic weights, or atomic numbers.
Categories described in the subsections below include ferrous and non-ferrous metals; brittle metals and refractory metals; heavy and light metals; and base, noble, and precious metals.

Cobalt

CoCo 2+ bush sickness
Some heavy metals are either essential nutrients (typically iron, cobalt, and zinc), or relatively harmless (such as ruthenium, silver, and indium), but can be toxic in larger amounts or certain forms.
The tobacco plant readily absorbs and accumulates heavy metals like cobalt from the surrounding soil in its leaves.

Metal toxicity

toxic metaltoxic metalsmetal poisoning
For more specific information see Metal toxicity, Toxic heavy metal, or the articles on individual elements or compounds.
Often heavy metals are thought as synonymous, but lighter metals may also be toxic in certain circumstances, such as beryllium and lithium.

Environmental impact of paint

Environmental issues with paintpaintsenvironmental hazards associated with paint
Potential sources of heavy metal poisoning include mining, tailings, industrial wastes, agricultural runoff, occupational exposure, paints and treated timber. Common sources of heavy metals in this context include mining and industrial wastes; vehicle emissions; lead-acid batteries; fertilisers; paints; and treated timber; aging water supply infrastructure; and microplastics floating in the world's oceans.
Heavy metals are used in paints and have raised concerns due to their toxicity at high levels of exposure and since they build up in the food chain.

Toxic heavy metal

heavy metal poisoningheavy metalsheavy metal
For more specific information see Metal toxicity, Toxic heavy metal, or the articles on individual elements or compounds. A deficiency of any of these period 4–6 essential heavy metals may increase susceptibility to heavy metal poisoning (conversely, an excess may also have adverse biological effects). Less-toxic heavy metals, such as copper, tin, tungsten, and bismuth, and probably manganese (as well as boron, a metalloid), have replaced lead and antimony in the green bullets used by some armies and in some recreational shooting munitions.
Heavy metals are found naturally in the earth.

R-process

r''-processr processR-
Rather, they are largely synthesised (from elements with a lower atomic number) by neutron capture, with the two main modes of this repetitive capture being the s-process and the r-process.
The rapid neutron-capture process, or so-called r-process, is a set of nuclear reactions that in nuclear astrophysics is responsible for the creation of approximately half of the atomic nuclei heavier than iron; the "heavy elements", with the other half produced by the p-process and s-process.

S-process

s''-processs-s process
Rather, they are largely synthesised (from elements with a lower atomic number) by neutron capture, with the two main modes of this repetitive capture being the s-process and the r-process.
The s-process is responsible for the creation (nucleosynthesis) of approximately half the atomic nuclei heavier than iron.

Microplastics

microplasticnurdlesMicroplastics ingested through diet
Common sources of heavy metals in this context include mining and industrial wastes; vehicle emissions; lead-acid batteries; fertilisers; paints; and treated timber; aging water supply infrastructure; and microplastics floating in the world's oceans.
As these scrubbers are used repeatedly until they diminish in size and their cutting power is lost, they often become contaminated with heavy metals such as cadmium, chromium, and lead.

Environmental chemistry

environmental chemistenvironmentalchemical environment
Metalloids meeting the applicable criteria–arsenic and antimony for example—are sometimes counted as heavy metals, particularly in environmental chemistry, as is the case here.
Chemical measures of water quality include dissolved oxygen (DO), chemical oxygen demand (COD), biochemical oxygen demand (BOD), total dissolved solids (TDS), pH, nutrients (nitrates and phosphorus), heavy metals, soil chemicals (including copper, zinc, cadmium, lead and mercury), and pesticides.

Flint water crisis

water crisisFlintcity's water crisis
Recent examples of heavy metal contamination and health risks include the occurrence of Minamata disease, in Japan (1932–1968; lawsuits ongoing as of 2016); the Bento Rodrigues dam disaster in Brazil, and high levels of lead in drinking water supplied to the residents of Flint, Michigan, in the north-east of the United States.
Because chlorine reacts with heavy metals like lead and iron, high levels of both in Flint's water may have been responsible for the decreased amount of chlorine available.

Europium

EuErEu 2+
Examples of such atomic properties include: partly filled d- or f- orbitals (in many of the transition, lanthanide, and actinide heavy metals) that enable the formation of coloured compounds; the capacity of most heavy metal ions (such as platinum, cerium or bismuth ) to exist in different oxidation states and therefore act as catalysts; poorly overlapping 3d or 4f orbitals (in iron, cobalt, and nickel, or the lanthanide heavy metals from europium through thulium) that give rise to magnetic effects; and high atomic numbers and electron densities that underpin their nuclear science applications.
Europium has no significant biological role and is relatively non-toxic compared to other heavy metals.

Aluminium

aluminumAlall-metal
From 1809 onward, light metals, such as magnesium, aluminium, and titanium, were discovered, as well as less well-known heavy metals including gallium, thallium, and hafnium.
In most people, aluminium is not as toxic as heavy metals.

Cadmium

CdCd 2+ cadmium compounds
Other heavy metals, such as cadmium, mercury, and lead, are highly poisonous.
The tobacco plant readily absorbs and accumulates heavy metals such as cadmium from the surrounding soil into its leaves.

Metalloid

metalloidsMetallicmetalloid staircase
The criteria used, and whether metalloids are included, vary depending on the author and context.
Further indications of a tendency for astatine to behave like a (heavy) metal are: "... the formation of pseudohalide compounds ... complexes of astatine cations ... complex anions of trivalent astatine ... as well as complexes with a variety of organic solvents".

Period 6 element

Period 666'''
In period 6, tungsten is required by some archaea and bacteria for metabolic processes.
Being a heavy metal, it leads to health issues upon exposure to its salts, but due to its corrosion resistance, it is not as toxic as some metals.

Silver

Agsilver orenative silver
The earliest known metals—common metals such as iron, copper, and tin, and precious metals such as silver, gold, and platinum—are heavy metals.
Silver compounds have low toxicity compared to those of most other heavy metals, as they are poorly absorbed by the human body when digested, and that which does get absorbed is rapidly converted to insoluble silver compounds or complexed by metallothionein.

Green bullet

green ammogreen bullets
Less-toxic heavy metals, such as copper, tin, tungsten, and bismuth, and probably manganese (as well as boron, a metalloid), have replaced lead and antimony in the green bullets used by some armies and in some recreational shooting munitions.
Initial objectives were elimination of ozone-depleting substances, volatile organic compounds, and heavy metals from primers and projectiles.

Oligodynamic effect

oligodynamicbiocidal properties of both copper and silversome heavy metals
The biocidal effects of some heavy metals have been known since antiquity.
The oligodynamic effect (from Greek oligos "few", and dynamis "force") is a biocidal effect of metals, especially heavy metals, that occurs even in low concentrations.

Copper

CuCu 2+ cupric
The earliest known metals—common metals such as iron, copper, and tin, and precious metals such as silver, gold, and platinum—are heavy metals.
The tobacco plant readily absorbs and accumulates heavy metals, such as copper from the surrounding soil into its leaves.

Minamata disease

Minamatamercury poisoning incidentMinamata disaster
Recent examples of heavy metal contamination and health risks include the occurrence of Minamata disease, in Japan (1932–1968; lawsuits ongoing as of 2016); the Bento Rodrigues dam disaster in Brazil, and high levels of lead in drinking water supplied to the residents of Flint, Michigan, in the north-east of the United States.
As soon as the investigation identified a heavy metal as the causal substance, the wastewater from the Chisso plant was immediately suspected as the origin.

Post-transition metal

other metalPost-transition metalsB metals
The United States Pharmacopeia includes a test for heavy metals that involves precipitating metallic impurities as their coloured sulfides." In 1997, Stephen Hawkes, a chemistry professor writing in the context of fifty years' experience with the term, said it applied to "metals with insoluble sulfides and hydroxides, whose salts produce colored solutions in water and whose complexes are usually colored". On the basis of the metals he had seen referred to as heavy metals, he suggested it would useful to define them as (in general) all the metals in periodic table columns 3 to 16 that are in row 4 or greater, in other words, the transition metals and post-transition metals. The lanthanides satisfy Hawkes' three-part description; the status of the actinides is not completely settled.
It is commonly regarded as a nonmetal, but is sometimes considered a metalloid or even a heavy metal.