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Abundance of the chemical elements - Wikipedia

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The abundance of elements in the Sun and outer planets is similar to that in the universe. Due to solar heating, the elements of Earth and the inner rocky planets of the Solar System have undergone an additional depletion of volatile hydrogen, helium, neon, nitrogen, and carbon (which volatilizes as methane).

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Many of the elements found throughout nature are also found within the body. This is the chemical composition of the average adult human body in terms of elements and also compounds.

Major Classes of Compounds in the Human Body

Most of the elements are found within compounds. Water and minerals are inorganic compounds. Organic compounds include fat, protein, carbohydrates, and nucleic acids.

Water: Water is the most abundant chemical compound in living human cells, accounting for 65 percent to 90 percent of each cell. It's also present between cells. For example, blood and cerebrospinal fluid are mostly water.

Fat: The percentage of fat varies from person to person, but even an obese person has more water than fat.

Protein: In a lean male, the percentages of protein and water are comparable. It's about 16 percent by mass. Muscles, including the heart, contain a lot of muscle. Hair and fingernails are protein. Skin contains a large amount of protein, too.

Minerals: Minerals account for about 6 percent of the body. They include salts and metals. Common minerals include sodium, chlorine, calcium, potassium, and iron.

Carbohydrates: Although humans use the sugar glucose as an energy source, there isn't that much of it free in the bloodstream at any given time. Sugar and other carbohydrates only account for about 1% of body mass.

Elements in the Human Body

Six elements account for 99% of the mass of the human body. The acronym CHNOPS may be used to help remember the six key chemical elements that are used in biological molecules. C is carbon, H is hydrogen, N is nitrogen, O is oxygen, P is phosphorus, and S is sulfur. While the acronym is a good way to remember the identities of the elements, it doesn't reflect their abundance.

Oxygen is the most abundant element in the human body accounting for approximately 65% of a person's mass. Each water molecule consists of two hydrogen atoms bonded to one oxygen atom, but the mass of each oxygen atom is much higher than the combined mass of the hydrogen. In addition to being a component of water, oxygen is essential for cellular respiration.

Carbon is contained in all organic compounds, which is why carbon is the second most abundant element in the body, accounting for about 18% of body mass. Carbon is found in proteins, carbohydrates, lipids, and nucleic acids. It's also found in carbon dioxide.

Hydrogen atoms are the most numerous type of atom in a human, but because they are so light, they only make up around 10% of the mass. Hydrogen is in water, plus it's an important electron carrier.

Nitrogen is about 3.3% of body mass. It's found in proteins and nucleic acids.

Calcium accounts for 1.5% of body mass. It's used to build bones and teeth, plus it's important for muscle contraction.

Phosphorus is about 1% of body mass. This element is found in nucleic acids. Breaking bonds connecting phosphate molecules is a major component of energy transfer.

Potassium is around 0.2-0.4% of the mass of a person. It's used in nerve conduction. Potassium is a key cation or positively-charged ion in the body.

Sulfur is found in some amino acids and proteins. It's about 0.2-0.3% of body mass.

Sodium, like potassium, is a positively-charged ion. It's about 0.1-0.2% of body mass. Sodium helps regulate the electrolyte balance in the body and maintain homeostasis with respect to the volume of water in the blood and cells.

Although aluminum and silicon are abundant in the earth's crust, they are found in trace amounts in the human body.

Other trace elements include metals, which are often cofactors for enzymes (e.g., cobalt for vitamin B₁₂). Trace elements include iron, cobalt, zinc, iodine, selenium, and flourine.

Does the Body Contain All the Elements?

The average human body contains tiny amounts of elements that serve no known biological function. These include germanium, antimony, silver, niobium, lanthanum, tellurium, bismuth, thallium, gold, and even radioactive elements like thorium, uranium, and radium. However, not all elements on the periodic table are found in the body. These are primarily the synthetic elements, which are made in laboratories. Even if they did occur in the body, most of the superheavy nuclei have such brief half-lives, they would decay into one of the more common elements almost instantly.

Anke M. (1986). "Arsenic". In: Mertz W. ed., Trace elements in human and Animal Nutrition, 5th ed. Orlando, FL: Academic Press. pp. 347-372.

Chang, Raymond (2007). Chemistry, Ninth Edition. McGraw-Hill. pp. 52.

Emsley, John (2011). Nature's Building Blocks: An A-Z Guide to the Elements. OUP Oxford. p. 83. ISBN 978-0-19-960563-7.

Subcommittee on the Tenth Edition of the Recommended Dietary Allowances, Food and Nutrition Board; Commission on Life Sciences, National Research Council (February 1989). Recommended Dietary Allowances: 10th Edition. National Academies Press. ISBN 978-0-309-04633-6.

Zumdahl, Steven S. and Susan A. (2000). Chemistry, Fifth Edition. Houghton Mifflin Company. p. 894. ISBN 0-395-98581-1.

Watch Now: 10 Surprising Mysteries About The Human Body

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Human Body Composition as Elements and Compounds

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Many of the elements found throughout nature are also found within the body. This is the chemical composition of the average adult human body in terms of elements and also compounds. Most of the elements are found within compounds. Water and minerals are inorganic compounds. Organic compounds include fat, protein, carbohydrates, and nucleic acids.

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Carbon is the foundation of all life on Earth, required to form complex molecules like proteins and DNA. This element is also found in our atmosphere in the form of carbon dioxide (CO2). Carbon helps to regulate the Earth's temperature, makes all life possible, is a key ingredient in the food that sustains us, and provides a major source of the energy to fuel our global economy.

The carbon cycle describes the process in which carbon atoms continually travel from the atmosphere to the Earth and then back into the atmosphere. Since our planet and its atmosphere form a closed environment, the amount of carbon in this system does not change. Where the carbon is located - in the atmosphere or on Earth - is constantly in flux.

On Earth, most carbon is stored in rocks and sediments, while the rest is located in the ocean, atmosphere, and in living organisms. These are the reservoirs, or sinks, through which carbon cycles.

Carbon is released back into the atmosphere when organisms die, volcanoes erupt, fires blaze, fossil fuels are burned, and through a variety of other mechanisms.

In the case of the ocean, carbon is continually exchanged between the ocean's surface waters and the atmosphere, or is stored for long periods of time in the ocean depths.

Humans play a major role in the carbon cycle through activities such as the burning of fossil fuels or land development. As a result, the amount of carbon dioxide in the atmosphere is rapidly rising; it is already considerably greater than at any time in the last 800,000 years.

Video Transcript

What is the carbon cycle? Carbon is the chemical backbone of all life on Earth. All of the carbon we currently have on Earth is the same amount we have always had. When new life is formed, carbon forms key molecules like protein and DNA. It's also found in our atmosphere in the form of carbon dioxide or CO2. The carbon cycle is nature's way of reusing carbon atoms, which travel from the atmosphere into organisms in the Earth and then back into the atmosphere over and over again. Most carbon is stored in rocks and sediments, while the rest is stored in the ocean, atmosphere, and living organisms. These are the reservoirs, or sinks, through which carbon cycles. The ocean is a giant carbon sink that absorbs carbon. Marine organisms from marsh plants to fish, from seaweed to birds, also produce carbon through living and dying. Sometimes dead organisms become fossil fuels that go through combustion, giving off CO2, and the cycle continues.

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national oceanic and atmospheric administration

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The carbon cycle describes the process in which carbon atoms continually travel from the atmosphere to the Earth and then back into the atmosphere. Since our planet and its atmosphere form a closed environment, the amount of carbon in this system does not change.

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Why it is important for Earth to cycle matter?

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Why it is important for Earth to cycle matter?

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How do cycles in nature maintain the stability of Earth 's climate?

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How do cycles in nature maintain the stability of Earth 's climate?

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Identify key nutrients that nature cycles.

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Identify key nutrients that nature cycles.

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For many households and businesses it is a daily
routine to recycle materials such as plastic,
aluminium, paper and glass. We do this in order to
conserve and protect important resources in our
environment.
But what about recycling in nature? How does nature
recycle material and nutrients (chemicals that
organisms need in order to live)?
Scientists do not use the term (recycling, in terms of nature.
Instead they use the term cycling or cycles.
Nature excels at cycling vital resources. It has to do so!
Earth has a fixed amount of matter. Matter is anything that
occupies space and has a mass. Therefore nature is continually
cycling matter to ensure that it can be used time and tin1e again. Two of the key resources that nature cycles are water and carbon. We will be looking at both
of these areas in nature and their importance to us and our planet.

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C.ro