View source for Carbon dioxide

[[Category: Chemistry]]
[[File:Carbon_dioxide_molecule.png|thumb|right|300px|Carbon dioxide molecule - CO<sub>2</sub>]]
== Explanation ==
Carbon dioxide ('''CO<sub>2</sub>''') is a compound made up of one [[carbon]] atom [[covalent bond|covalently]] [[double bond|double bonded]] to two [[oxygen]] atoms. Though it naturally occurs in trace amounts in the [[Earth]]'s atmosphere, primary sources of carbon dioxide include [[combustion]] of [[organic compound]]s like wood, [[aerobic organism|aerobic]] respiration, and [[fermentation]] of sugars. Carbon dioxide plays a vital role in plants and bacteria, where they synthesize [[carbohydrate]] from carbon dioxide and [[water]] with the help of light energy from the [[Sun]].

== Frequently Asked Questions ==
=== What is the biological importance of carbon dioxide? ===
In biological energy chemistry, carbon dioxide is important because it represents an "energetically exhausted" carbon molecule, or the end product of energy harvesting of sugars and fats. Briefly, electrons in C-H and C-C bonds (common in sugars and fats) are in relatively high energy [[orbital]]s, whereas those in C-O bonds are relatively low energy. The processes of respiration and the electron transport chain 'harvest' high energy electrons and convert their energy to other forms. The rearrangements involved result in products CO<sub>2</sub> and H<sub>2</sub>O--all electrons are 'spent'.

CO<sub>2</sub> is also biologically important because it allows sunlight to pass through readily (visible wavelengths of light), but it reflects warmth (infrared wavelengths). More CO<sub>2</sub> in the atmosphere, therefore, traps more [[heat]] while not decreasing the amount of sunlight energy coming to the planet ([[greenhouse effect]]).