carbon

Name carbon
Symbol C
Atomic Weight 12.0107
Atomic Number 6
CAS ID 7440-44-0
Group Number 14
Group Name (none)
Period Number 2
Origin of Name Latin, carbo = "charcoal."
Year Discovered Prehistoric
Discovery Credits Known to prehistoric humans.
Class Non-Metallic
Color Graphite is black, diamond is colorless
Standard State Solid at 77 F & 298 K
Description Present as 4 allotropes. Used as coke (steel making), carbon black (printing), and activated charcoal (sugar refining, etc.). The radioactive isotope, C14, is produced in the atmosphere by cosmic ray bombardment of N14 and is not found in carbon-bearing minerals derived from atmospheric CO2 older than 70,000 years.

Diagnostic tests: 
As the carbonate (CO32-), effloresces in dilute HCl with the evolution of colorless and odorless CO2 gas.
As the hydrocarbon, burns in air or O2.
As the element, carbon can be identified from physical properties (diamond, graphite). You can burn a diamond or graphite with difficulty by heating it to red heat in an O2 atmosphere where it will leave none or very little residue.

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