materiały: Carbon

Evidence: 100 • authority: 72

Carbon (from Latin carbo 'coal') is a chemical element; it has symbol C and atomic number 6. It is nonmetallic and tetravalent—meaning that its atoms are able to form up to four covalent bonds due to its valence shell exhibiting 4 electrons. It belongs to group 14 of the periodic table. Carbon makes up about 0.025 percent of Earth's crust. Three isotopes occur naturally, 12C and 13C being stable, while 14C is a radionuclide, decaying with a half-life of 5,700 years. Carbon is one of the few elements known since antiquity. Carbon is the 15th most abundant element in the Earth's crust, and the fourth most abundant element in the universe by mass after hydrogen, helium, and oxygen. Carbon's ab…

Evidence: 67 • authority: 72

Several forms of biochemistry are agreed to be scientifically viable, but are not proven to exist at this time. The kinds of living organisms known on Earth, as of 2026, all use carbon compounds for basic structural and metabolic functions, water as a solvent, and deoxyribonucleic acid (DNA) or ribonucleic acid (RNA) to define and control their form. If life exists on other celestial bodies (planets, moons), it may be chemically similar, though it is also possible that there are organisms with quite different chemistries – for instance, involving other classes of carbon compounds, compounds of another element, and/or another solvent in place of water. The possibility of life-forms being bas…

Evidence: 61 • authority: 72

Kerogen is solid, insoluble organic matter in sedimentary rocks. It consists of a variety of organic materials, including dead plants, algae, and other microorganisms, that have been compressed and heated by geological processes. All the kerogen on earth is estimated to contain 1016 tons of carbon. This makes it the most abundant source of organic compounds on earth, exceeding the total organic content of living matter 10,000-fold. The type of kerogen present in a particular rock formation depends on the type of organic material that was originally present. Kerogen can be classified by these origins: lacustrine (e.g., algal), marine (e.g., planktonic), and terrestrial (e.g., pollen and spor…

Evidence: 61 • authority: 72

Carbon-based life is the concept that carbon is the core element for all known forms of life, and a core component of all complex biological molecules with carbon representing approximately 45–50% of all dry biomass. Complex biological molecules consist of carbon atoms bonded with other elements, in particular oxygen and hydrogen but frequently also nitrogen, phosphorus, and sulfur (collectively known as CHNOPS). In these molecules carbon's four valence electrons and subsequent propensity to form four bonds lends to its function as the "skeleton" of organic molecules. In addition to molecular level properties of carbon, life on Earth also relies on large scale processes known as the carbon…

Evidence: 56 • authority: 88

Sources of Organic Compounds Required for Primitive Life. Carbon compounds on the early Earth were not the simple mixture previously referred to as a “prebiotic soup.” Instead, there was a continuing input of organic material synthesized by geochemical and photochemical reactions in the volcanic crust and atmosphere; organic compounds were also being delivered during late accretion by the infall of interplanetary dust particles (IDPs), impacting comets, and asteroid-sized bodies. Compounds from both sources (terrestrial and not) then underwent chemical processing by volcanism, photochemistry, and mineral-driven oxidation–reduction reactions. Some of these processes were synthetic reactions…

Evidence: 56 • authority: 72

The history of life on Earth traces the processes by which living and extinct organisms evolved, from the earliest emergence of life to the present day. Earth formed about 4.54 ± 0.05 billion years ago (abbreviated as Ga, for gigaannum) and evidence suggests that life emerged prior to 3.7 Ga. The similarities among all known present-day species indicate that they have diverged through the process of evolution from a common ancestor. The earliest clear evidence of life comes from biogenic carbon signatures and stromatolite fossils discovered in 3.7 billion-year-old metasedimentary rocks from western Greenland. In 2015, possible "remains of biotic life" were found in 4.1 billion-year-old rock…

Evidence: 45 • authority: 80

SECTION D – CARBON, THE BASIS FOR LIFE ON EARTH D2 Naming organic compounds

Evidence: 40 • authority: 72

Silver is a chemical element; it has symbol Ag (from Latin argentum) and atomic number 47. A soft, white, lustrous transition metal, it exhibits the highest electrical conductivity, thermal conductivity and reflectivity of any metal. Silver is found in the Earth's crust in the pure, free elemental form ("native silver"), as an alloy with gold (electrum) and other metals, and in minerals such as acanthite, argentite and chlorargyrite. Most silver is recovered as a byproduct of lead–zinc, copper and gold mining and refining. Silver has long been valued as a precious metal and coinage metal. It is one of the seven metals of antiquity, and has had an enduring role in monetary systems, jewellery…

Evidence: 40 • authority: 92

Mechanisms of Microplastic Effects on Carbon and Nitrogen Cycling in Aquatic and Terrestrial Ecosystems.. An emerging environmental pollutant, microplastics have garnered global attention due to their widespread presence in soil and aquatic ecosystems. Early research primarily treated microplastics as single pollutants, focusing on their individual toxic effects. However, microplastics in the environment exist as a complex mixture, comprising various polymer types, sizes, shapes, and aging states. This diversity influences how microplastics regulate ecosystem carbon and nitrogen cycles and intervene through pathways such as direct carbon input, physical disturbance, microbial community rest…

Evidence: 40 • authority: 92

Functional abiotic metabolite assembly hypothesis for the early events in the origin of life.. The RNA world hypothesis provides a compelling framework for the emergence of life, yet a fundamental gap remains between simple abiotic molecules and complex functional RNA polymers. Here, we propose the Functional Abiotic Metabolite Assembly hypothesis, in which simple prebiotically abundant molecules, particularly amino acids and nucleobases, preceded peptides and RNA as self-organizing functional entities. Unlike peptides, which are rarely detected in abiotic contexts, metabolite-like molecules are readily found in meteorites and early Earth simulations and can self-assemble into ordered, amyl…

Evidence: 34 • authority: 80

Can Linear Conjugated Polymers Form Stable Helical Structures on the Carbon Nanotubes?

Evidence: 34 • authority: 80

Doping Strategy To Boost the Electromagnetic Wave Attenuation Ability of Hollow Carbon Spheres at Elevated Temperatures