Chai's posts

Atomic radius – 70pm (empirical), 67 pm (calculated)
Ionic radius – C4 29pm

Electronegativity refers to the power of an atom within a molecule to attract electron density to itself.
- Many factors, including other atoms within the molecule, number of atoms corradiated to it, and the oxidation number for the atom.
Electronegativity has no units, however, is often measured by “Pauling Units”, as indicated by units mapped via the Pauling Scale (a range of about 0.7 (Hydrogen) to 3.98 (Fluorine)). Carbon has an electronegativity of 2.55 on this scale, putting it at roughly the center.

The first scale, and most widely used, is the Pauling Electronegativity Scale (χr), invented by Linus Pauling in 1932. (The concept of electronegativity existing between elements dates back to the early 1800s, however) Pauling proposed that the concept of electronegativity is based around the fact that covalent bonds between two different atoms (represented by (A-B), is stronger than expected, by taking the strengths of the A-A and B-B bonds.

Mulliken Electronegativity was proposed by Robert S. Mulliken, theorizing that the arithmetic mean of the first ionizing energy (represented by Ei) and the electron affinity (represented by Eea) should measure the tendency of an atom to attract electrons. This has also been termed “absolute electronegativity”, using kilojoules per mole or electronvolts as measurements. 2.48 (sp^3 orbital) Pauling Units.

Allred-Rochow electronegativity, proposed by A. Louis Allred and Eugene G. Roschow, was based around the idea that electronegativity should be related to the charge ecperiecnced by an electron on the “Surface” of the atom – the higher the charge per unit area of the atomic surface, the greater the tendancy of that atom to attract electrons. 2.50 Pauling units.

Sanderson Electronegativity proposes that there is a relationship between Mulliken electronegativity and the atomic size, creating a calculation based on the reciprocal of the atomic volume. This allows estimation of bond energies in a wide range of compounds, as well as being used to calculate molecular geometry, s-electrons energy, NMR spin-spin constants and other parameters for organic compounds. This theory is also part of the concept of electronegativity equalization, suggesting that electrons tend to distribute themselves around a molecule to minimize or equalize Mulliken’s electronegativity. 2.75 Pauling Units.

Allen Electronegativity, proposed by Leland C. Allen, suggested that an element’s electronegativity is related to the average energy of the valence electrons(the outer shell electron associated with an atom) in a free atom. 2.54 Pauling Units.

Molar ionizing energies:
1086.5
2352.6
4620.5
6222.7
37,831
47,277.0
(kJ/mol (KiloJoules/Mole))

Six elements (Oxygen, Carbon, Hydrogen, Nitrogen and Phosphorous (O, C, H, N, P)) make up approximately 99% of Human body mass. Carbon makes up 18.5% of this mass, making it the second most abundant element in human body (O being the most abundant at about 65%) *The remainder of the body (0.85%) is composed of another five elements: potassium, sulfur, sodium, chlorine, and magnesium! (K, S, Na, Cl, Mg)*

Elemental carbon is of low toxicity, health hazards being indicated by Carbon compounds, such as carbon Monoxide (CO) and Cyanide (CN). There is also Carbon-14, a radioactive isotope, with a half-life of approx. 5,730 years and is primarily used in Radiocarbon dating methods. Carbon can form a vast amount of compounds, outnumbering any other element, with an estimated almost ten million to date!

Biological system, yes, Carbon makes up 18.5% of human body and is responsible for regulating the temperature in biological systems (Global Warming? That’s Carbon! CO2 levels causing temperature increases). Carbon transports Oxygen through these systems as well. Carbon is found in ALL organic molecules, often being said that all life on the planet is based in Carbon (hence the term “Carbon-based lifeform").

Petroleum industries, yes. Petroleum is made up of several Hydrocarbon (Hydrogen and Carbon organic compounds) of varying weights.

Pharmaceuticals--absolutely. Charcoal face masks? Carbon, baby! (Activated) carbon is most often used as a means of purification and absorption (oils in the skin/hair) and moisture control. Also a big factor in hair care and dental products (again with the charcoal – people LOVE the charcoal toothpaste because of its ability to supposedly “attract” the stains from teeth and leave them sparkling white). Carbon is used in painkillers, such as Asprin (CO2H). Electronics, yes! Also used in structural bodies, such as carbon fiber. Also, diamonds! Plastics! What can’t carbon do, honestly?

Availability kinda included above, buuuut…Charcoal masks, charcoal for grilling, carbon fibers, petroleum, plastics, diamond jewelry, etc. etc.