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How do geologists use carbon dating to find the age of rocks ? •Geologists do not use carbon-based radiometric dating to determine the age of rocks.  •Carbon dating only works for objects that are younger than about 50,000 years, and most rocks of interest are older than that. •Carbon dating is used by archeologists to date trees, plants, and animal remains; as well as human artifacts made from wood and leather; because these items are generally younger than 50,000 years. •Carbon is found in different forms in the environment – mainly in the stable form of carbon-12 and the unstable form of carbon-14.  •Over time, carbon-14 decays radioactively and turns into nitrogen. •A living organism takes in both carbon-12 and carbon-14 from the environment in the same relative proportion that they existed naturally.  •Once the organism dies, it stops replenishing its carbon supply, and the total carbon-14 content in the organism slowly disappears.  •Scientists can de...

Why is lead used in pencils even though lead is poisonous ? •The core of a pencil does not contain lead and never has. Pencils contain a form of solid carbon known as graphite.  •According to a study, the graphite pencil was first developed and popularized in the 1600's.  •The first users of graphite simply dug this mineral out of the hills and discovered it could be sawed into sticks and used as an excellent writing tool.  •During the 1600's, no one knew the chemical nature of this material, as chemistry itself was still in its infancy. •Since this writing material behaved similar to metallic lead, but had a darker color, people began calling it "black lead".  •Eventually, the name of the core of the pencil got shortened to "lead". In 1779, German chemist K. W. Scheele finally determined pencil lead to be composed of pure carbon.  •A decade later, A. G. Werner decided that this carbon material needed a new name and proposed the name "graphi...

Why do diamonds last forever ? •Diamonds do not last forever. Diamonds degrade to graphite, because graphite is a lower-energy configuration under typical conditions. •Diamond (the stuff in wedding rings) and graphite (the stuff in pencils) are both crystalline forms of pure carbon. •The only difference is the way the carbon atoms are arranged and bonded in the crystalline lattice. •In diamond, each carbon atom is bonded to four neighboring carbon atoms in a closely-packed three-dimensional grid. •In graphite, each carbon atom is strongly bonded to three neighboring carbon atoms in a plane and the planes of atoms are loosely bonded to each other. •The degradation of diamond to graphite is a simple case of the atoms internally rearranging and relaxing to a lower energy state. This process requires no chemical reaction with an external material. •Although graphite is a more stable form of crystalline carbon than diamond under normal conditions, there is a significant kinetic ...