Teacher:Given a passage and a query based on the passage, generate an unambiguous, concise and simple answer to the query from information in the passage. Note that the answer may not be present in exact form.
Teacher: Now, understand the problem? Solve this instance: The chemistry of calcium is that of a typical heavy alkaline earth metal. For example, calcium spontaneously reacts with water more quickly than magnesium and less quickly than strontium to produce calcium hydroxide and hydrogen gas. At 3%, calcium is the fifth most abundant element in the Earth's crust, and the third most abundant metal behind aluminium and iron. It is also the fourth most abundant element in the lunar highlands. Calcium is a chemical element with symbol Ca and atomic number 20. An alkaline earth metal, calcium is a reactive pale yellow metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to its heavier homologues strontium and barium. It is the fifth most abundant element in Earth's crust and the third most abundant metal, after iron and aluminium. The most common calcium compound on Earth is calcium carbonate, found in limestone and the Calcium has four basic functions in the soil which help to create better soil structure and healthy plants. Calcium is an alkaline metal of Group II A on the periodic chart and is the fifth most abundant element in the earth's crust while being widely distributed in nature. The electronic structure of the calcium cation makes it a unique element that is ideally suited to assist in plant growth. Calcium is the fifth most abundant element in the human body and the most abundant metal. Calcium ions play a vital role in the physiology and biochemistry of organisms and the cell as electrolytes. Calcium (Ca), chemical element, one of the alkaline-earth metals of Group 2 (IIa) of the periodic table. It is the most abundant metallic element in the human body and the fifth most abundant element in Earth's crust. More recent papers have confirmed this observation, demonstrating that seawater Ca 2+ concentration is not constant, and that the ocean is never in a steady state with respect to calcium input and output. This has important climatological implications, as the marine calcium cycle is closely tied to the carbon cycle. Calcium is the fifth most abundant chemical element in Earth's crust. It also makes up 2 percent of the human body. In the body calcium helps form bones and teeth and keeps them healthy. It is also present in the blood and in nerve cells. Scientists use symbols to stand for the chemical elements. by Jim Halbeisen. Calcium is an alkaline metal of Group II A on the periodic chart and is the fifth most abundant element in the earth's crust while being widely distributed in nature. The electronic structure of the calcium cation makes it a unique element that is ideally suited to assist in plant growth. Occurrence, properties, and uses. 1 Calcium does not occur naturally in the free state, but compounds of the element are widely distributed. One calcium compound, lime (calcium oxide, CaO) was extensively used by the ancients. Query: how important is calcium on earth
Student:
An alkaline earth metal, calcium is a reactive pale yellow metal that forms a dark oxide-nitride layer when exposed to air.