Carbon is an incredible element. Arrange carbon atoms in one way, and they become soft, pliable graphite. Re-jigger the arrangement, and — presto! — the atoms form diamond, one of the hardest. 36,295 carbon atom stock photos, vectors, and illustrations are available royalty-free. See carbon atom stock video clips. Element carbon atomic structure carbon atomic structure vector atoms the atom carbon molecule atom diagram electron atomo an atom protons neutrons electrons carbon. Carbon contains four electrons in its outer shell. Therefore, it can form four covalent bonds with other atoms or molecules. The simplest organic carbon molecule is methane (CH 4), in which four hydrogen atoms bind to a carbon atom (Figure 1). However, structures that. It is interesting to note the carbon atom has 6 electrons, 6 protons and 6 neutrons. The graphic represents a model for the carbon atom. This is the base atomic structure of our elemental body on the earth. Protons, electrons and neutrons build elements in a straight forward manner. For each additional proton, a new element is created. Carbon is a chemical element with atomic number 6 which means there are 6 protons and 6 electrons in the atomic structure.The chemical symbol for Carbon is C. It is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds.
Learning Outcomes
- Discuss why it is said that life is carbon-based and the bonding properties of carbon.
Carbon
Living things are carbon-based because carbon plays such a prominent role in the chemistry of living things. This means that carbon atoms, bonded to other carbon atoms or other elements, form the fundamental components of many, if not most, of the molecules found uniquely in living things. Other elements play important roles in biological molecules, but carbon certainly qualifies as the “foundation” element for molecules in living things. It is the bonding properties of carbon atoms that are responsible for its important role.
Carbon Bonding
The four covalent bonding positions of the carbon atom can give rise to a wide diversity of compounds with many functions, accounting for the importance of carbon in living things.
Carbon contains four electrons in its outer shell. Therefore, it can form four covalent bonds with other atoms or molecules. The simplest organic carbon molecule is methane (CH4), in which four hydrogen atoms bind to a carbon atom (Figure 1).
However, structures that are more complex are made using carbon. Any of the hydrogen atoms can be replaced with another carbon atom covalently bonded to the first carbon atom. In this way, long and branching chains of carbon compounds can be made (Figure 2a). The carbon atoms may bond with atoms of other elements, such as nitrogen, oxygen, and phosphorus (Figure 2b). The molecules may also form rings, which themselves can link with other rings (Figure 2c). This diversity of molecular forms accounts for the diversity of functions of the biological macromolecules and is based to a large degree on the ability of carbon to form multiple bonds with itself and other atoms.
Figure 2. These examples show three molecules (found in living organisms) that contain carbon atoms bonded in various ways to other carbon atoms and the atoms of other elements. (a) This molecule of stearic acid has a long chain of carbon atoms. (b) Glycine, a component of proteins, contains carbon, nitrogen, oxygen, and hydrogen atoms. (c) Glucose, a sugar, has a ring of carbon atoms and one oxygen atom.
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A carbonyl group is a chemically organic functional group composed of a carbon atom double-bonded to an oxygen atom --> [C=O Drivers akonii. ] The simplest carbonyl groups are aldehydes and ketones usually attached to another carbon compound. These structures can be found in many aromatic compounds contributing to smell and taste.
Introduction
Before going into anything in depth be sure to understand that the C=O entity itself is known as the 'Carbonyl group' while the members of this group are called 'carbonyl compounds' --> X-C=O. The carbon and oxygen are usually sp2hybridized and planar.
Carbonyl Group Double Bonds
The double bonds in alkenes and double bonds in carbonyl groups are VERY different in terms of reactivity. The C=C is less reactive due to C=O electronegativity attributed to the oxygen and its two lone pairs of electrons. One pair of the oxygen lone pairs are located in 2s while the other pair are in 2p orbital where its axis is directed perpendicular to the direction of the pi orbitals. The Carbonyl groups properties are directly tied to its electronic structure as well as geometric positioning. For example, the electronegativity of oxygen also polarizes the pi bond allowing the single bonded substituent connected to become electron withdrawing.
*Note: Both the pi bonds are in phase (top and botom blue ovals)
The double bond lengths of a carbonyl group is about 1.2 angstroms and the strength is about 176-179 kcal/mol). It is possible to correlate the length of a carbonyl bond with its polarity; the longer the bond meaing the lower the polarity. For example, the bond length in C=O is larger in acetaldehyde than in formaldehyde (this of course takes into account the inductive effect of CH3 in the compound).
Polarization
As discussed before, we understand that oxygen has two lone pairs of electrons hanging around. These electrons make the oxygen more electronegative than carbon. The carbon is then partially postive (electrophillic) and the oxygen partially negative (nucleophillic). The polarizability is denoted by a lowercase delta and a positive or negative superscript depending. For example, carbon would have d+ and oxygen delta^(-). The polarization of carbonyl groups also effects the boiling point of aldehydes and ketones to be higher than those of hydrocarbons in the same amount. The larger the carbonyl compound the less soluble it is in water. If the compound exceeds six carbons it then becomes insoluble.
*For more information about carbonyl solubility, look in the 'outside links' section
Carbon Atom Model
*Amides are the most stable of the carbonyl couplings due to the high-resonance stabilization between nitrogen-carbon and carbon-oxygen.
Nucleophile Addition to a Carbonyl Group
C=O is prone to additions and nucleophillic attack because or carbon's positive charge and oxygen's negative charge. The resonance of the carbon partial positive charge allows the negative charge on the nucleophile to attack the Carbonyl group and become a part of the structure and a positive charge (usually a proton hydrogen) attacks the oxygen. Just a reminder, the nucleophile is a good acid therefore 'likes protons' so it will attack the side with a positive charge.
*Remember: due to the electronegative nature of oxygen the carbon is partially positive and oxygen is partially negative
1 2 3
- The Nucleophile (Nu) attacks the positively charged carbon and pushes one of the double bond electrons onto oxygen to give it a negative charge.
- The Nucleophile is now a part of the carbonl structure with a negatively cahrged oxygen and a Na+ 'floating' around.
- The negatively charged oxygen attacks the proton (H+) to give the resulting product above.
Problems
- What is the hybridization of the carbon in the C=O? the oxygen?
- Illustrate the correct partial positive/negative or polarization of a formaldehyde.
- Is carboxylic acid soluble in water? enone? acetaldehyde?
Answers
1. sp2;sp2
Carbon Atom
2. partial positive on the carbon and partial negative on the oxygen
3. yes; yes; yes
References
Carbon Atomic Mass
- Patai, Saul, ed. The Chemistry of the Carbonyl Group. Vol. 1. London-New York-Sydney: Interscience, 1966.
- Zabicky, Jacob, ed. The Chemistry of the Carbonyl Group. Vol. 2. London-New York-Sydney: Interscience, 1966.
- Gutsche, C. David, author. Rinehart, Kenneth L., ed. The Chemistry of Carbonyl Groups. Vol.1 Endlewood Cliffs, New Jersey: Prentice-Hall, Inc., 1967
- Vollhardt, K. Peter C. 'The Carbonyl Group (17.2).' Organic chemistry structure and function. 5th ed. Vol. 1. New York: W.H. Freeman, 2007.