Editing Carbon group (section)

==Occurrence==
Carbon accumulates as the result of [[stellar fusion]] in most stars, even small ones.<ref name = "The Disappearing Spoon"/> Carbon is present in the Earth's crust in concentrations of 480 parts per million, and is present in [[seawater]] at concentrations of 28 parts per million. Carbon is present in the atmosphere in the form of [[carbon monoxide]], [[carbon dioxide]], and [[methane]]. Carbon is a key constituent of [[carbonate minerals]], and is in [[hydrogen carbonate]], which is common in seawater. Carbon forms 22.8% of a typical human.<ref name = "Nature's Building Blocks"/>

Silicon is present in the Earth's crust at concentrations of 28%, making it the second most abundant element there. Silicon's concentration in seawater can vary from 30 parts per billion on the surface of the ocean to 2000 parts per billion deeper down. Silicon dust occurs in trace amounts in Earth's atmosphere. [[Silicate minerals]] are the most common type of mineral on earth. Silicon makes up 14.3 parts per million of the human body on average.<ref name = "Nature's Building Blocks"/> Only the largest stars produce silicon via stellar fusion.<ref name = "The Disappearing Spoon"/>

Germanium makes up 2 parts per million of the Earth's crust, making it the 52nd most abundant element there. On average, germanium makes up 1 part per million of [[soil]]. Germanium makes up 0.5 parts per trillion of seawater. [[Organogermanium chemistry|Organogermanium compounds]] are also found in seawater. Germanium occurs in the human body at concentrations of 71.4 parts per billion. Germanium has been found to exist in some very faraway stars.<ref name = "Nature's Building Blocks"/>

Tin makes up 2 parts per million of the Earth's crust, making it the 49th most abundant element there. On average, tin makes up 1 part per million of soil. Tin exists in seawater at concentrations of 4 parts per trillion. Tin makes up 428 parts per billion of the human body. [[Tin(IV) oxide]] occurs at concentrations of 0.1 to 300 parts per million in soils.<ref name = "Nature's Building Blocks"/> Tin also occurs in concentrations of one part per thousand in [[igneous rock]]s.<ref>{{Citation|url = https://www.britannica.com/EBchecked/topic/596431/tin-Sn|title = tin (Sn)|year = 2013|access-date = February 24, 2013|publisher = [[Encyclopædia Britannica]]}}</ref>

Lead makes up 14 parts per million of the Earth's crust, making it the 36th most abundant element there. On average, lead makes up 23 parts per million of soil, but the concentration can reach 20000 parts per million (2 percent) near old lead mines. Lead exists in seawater at concentrations of 2 parts per trillion. Lead makes up 1.7 parts per million of the human body by weight. Human activity releases more lead into the environment than any other metal.<ref name = "Nature's Building Blocks"/>

Flerovium doesn't occur in nature at all, so it only exists in [[particle accelerators]] with a few atoms at a time.<ref name = "Nature's Building Blocks"/>