Heavy metals and their effects on the environment and biosphere It is crucial to note that several trace elements in the heavy metal family are required for many biological activities; they are mostly found in Period 4 of the periodic table of elements. The term "heavy metal" refers to any chemical element with a density greater than 5 g/cm3. Heavy metals are often referred to as metalloids because they contain both metallic properties (such as resistance to oxidation) and non-metallic properties (such as carbon's ability to conduct electricity). Heavy metals occur in nature as sulfides, oxides, or elemental states. They are usually found in rock formations or in soil, but some can also be found in water bodies like lakes or oceans. Heavy metals have been used for centuries without much concern for environmental impact because they were considered to be too small of an issue to matter.
The most common heavy metals found in the environment are mercury, arsenic, cadmium, and lead. Others include zinc, copper, iron, and nickel. These elements are all around us. We breathe in air containing oxygen which contains heavy metals such as arsenic, cadmium, and mercury. Animals eat these plants and then humans eat these animals who have eaten these plants. This cycle continues until the heavy metals reach places where they cannot be released into the environment easily.
The abundance of chemical elements is a measure of the abundance of chemical elements in comparison to all other elements in a particular environment. The quantity of chemical elements in the cosmos is dominated by the vast quantities of hydrogen and helium created during the Big Bang. Other abundant elements include carbon, oxygen, nitrogen, phosphorus, sulfur, and iron.
Abundance can be expressed as a percentage or on a mass basis. On a percentage basis, the most abundant element in the Earth's crust by weight is oxygen (66.6%). On a mass basis, the most abundant element in the Earth's crust is silicon (49.3%). The next most abundant elements are iron (15.4%), oxygen (14.9%), magnesium (11.1%), aluminum (10.8%), calcium (10.4%), potassium (10.0%), sodium ( 9.7%), zinc ( 8.5%), copper ( 7.7%), chlorine ( 7.4%), nickel ( 6.9%), manganese ( 6.4%), europium ( 5.7%), ytterbium ( 5.5%), hafnium ( 5.3%), tungsten ( 5.1%), rhenium ( 4.6%), zinc ( 4.4%), chrome ( 4.2%), iridium ( 3.9%), platinum ( 3.8%), gold ( 3.7%).
Metallic elements are located on the periodic table's left side. They are indicated by a black box next to the element symbol.
The following metals are included in the table: Ag, Al, Au, Ca, Ce, Cd, Co, Cr, Cu, Fe, Ga, Ge, Gd, Gr, Hg, Ho, Ir, K, La, Li, Mg, Mn, Mo, Na, Nb, Ni, O, P, Pt, Rh, Ru, S, Sc, Se, Si, Sm, Sn, Sr, Ta, Te, Tc, Ti, V, W, Xe, Y and Zn.
Alloys containing these elements are also metallic.
Metals are usually soft, malleable, and ductile. Alloys can be harder, more brittle or less hard depending on their composition.
Metals have good electrical and thermal conductivity. Alloys may have lower or higher conductivities than their constituent metals.
Metals are found in all living organisms. Some are essential for human health (such as zinc and iron), while others are not (such as mercury).
There are around 60 chemical components contained in the body, although it is unknown what all of them do. Approximately 96 percent of the mass of the human body is made up of only four elements: oxygen, carbon, hydrogen, and nitrogen, with water accounting for a major amount of that. The other elements are present in small amounts.
Of the known chemical elements, only hydrogen, helium, oxygen, silicon, sulfur, phosphorus, iron, magnesium, calcium, potassium, sodium, zinc, chromium, nickel, copper, manganese, aluminum, vanadium, ruthenium, osmium, iridium, platinum, and radon are found in the human body. All the others are either not present or present in quantities too small to be detected by current technology.
The most abundant element in the human body is hydrogen, which makes up about 75% of our weight. Next comes oxygen, which makes up about 25% of our weight. These two elements alone account for nearly every other element found in the body as well. All the other elements are present in smaller quantities.
In conclusion, the human body contains about 60 chemical elements. Of these, only 4 elements account for more than 1%.
Uranium is the heaviest naturally occurring element. It has the chemical symbol U and the atomic number 92. It is a silvery-white metal in the periodic table's actinide series. Uranium is used to make fuel cells, lasers, and nuclear weapons.
Elements with an atomic mass of 238 or greater are called heavy elements. Elements that exist in nature are usually lighter versions of these heavier elements. For example, hydrogen is one of the lightest elements and exists as a gas at room temperature and pressure. It is also the first element listed on the periodic table. Helium is a second light element and exists only as a gas at room temperature and pressure. Both uranium and thorium are found in nature in the form of raw ore. Only uranium ores contain any significant amount of gold; however, thorium ore contains significant amounts of silver, platinum group metals, zinc, copper, and lithium.
Heavy elements can be created in laboratories using particle accelerators. Scientists have also discovered ways of synthesizing heavier elements from other materials. For example, scientists have shown that they can make uranium artificially by reacting lead with sodium compounds in a furnace at high temperatures.
Theoretically, it should be possible to weigh all the atoms in a piece of uranium and still have some left over.
The periodic table's metals list contains iron, lead, gold, aluminum, platinum, uranium, zinc, lithium, sodium, tin, silver, and so on. The periodic table's nonmetals list contains hydrogen, helium, carbon, sulfur, nitrogen, oxygen, radon, neon, various halogens, and noble gases, among others.
Metals are chemical elements that have the ability to conduct electricity and are used in almost all technologies today. Non-conducting materials such as wood, plastic, glass, ceramics, and rubber do not conduct electricity and are called insulators. Metals can be divided into two main groups: conductors and semiconductors. Conductors such as copper, silver, gold, and platinum are electrons magnets that attract other electrons from other atoms or molecules. They require energy to become polarized - the state where an electron moves around a nucleus - but once this energy is removed they return to their original state. Semiconductors such as silicon, germanium, arsenic, phosphorus, and zinc are electrons magnets that attract other electrons but do not quite reach a net charge. They need energy to become polarized but then remain in this state unless an external force acts upon them. Examples of conductors and semiconductors are shown below.
Conductors cannot exist by themselves; they must be combined with non-conductors to make materials useful for building things.