Carbon is considered which of the following

This means that the refractive indices for red and violet light are different 2. As a result, the gemstone acts like a prism to separate white light into rainbow colors, and its dispersion is 0. The greater the dispersion, the better the spectrum of colors that is obtained. This property gives rise to the "fire" of diamonds.

The "brilliance" of diamonds stems from a combination of refraction, internal reflection and dispersion of light. For yellow light, for example, diamond has a high refractive index, 2. This means that when yellow light passes into a diamond and hits a second face internally at an angle greater than The carbon atoms in graphite are also arranged in an infinite array, but they are layered. These atoms have two types of interactions with one another. In the first, each carbon atom is bonded to three other carbon atoms and arranged at the corners of a network of regular hexagons with a degree C-C-C bond angle.

These planar arrangements extend in two dimensions to form a horizontal, hexagonal "chicken-wire" array. In addition, these planar arrays are held together by weaker forces known as stacking interactions.

The distance between two layers is longer 3. This three-dimensional structure accounts for the physical properties of graphite. Unlike diamond, graphite can be used as a lubricant or in pencils because the layers cleave readily.

It is soft and slippery, and its hardness is less than one on the Mohs scale. The four most abundant elements in the human body — hydrogen, oxygen, carbon and nitrogen — account for more than 99 per cent of the atoms inside you. They are found throughout your body, mostly as water but also as components of biomolecules such as proteins, fats, DNA and carbohydrates.

Magnesium is a key component of superoxide dismutase, one of the most important detoxification enzymes. Strontium is found almost exclusively in bones, where it may have a benefcial effect on growth and density. Iodine is an essential component of the thyroid hormone thyroxine. There are, however, national and international programs that certify and label products and materials based on their indoor air quality impacts such as various human health and comfort effects including odor, irritation, chronic toxicity, or carcinogenicity.

Such programs are likely to include consideration of at least some of the VOCs of concern for indoor air. However, the norms and requirements currently used within the product labeling and certification industry for indoor products are not standardized. The government or third-party organization has not yet established the ground rules to craft consistent, protective standard test methods to rate and compare products and materials.

This lack of standardization makes it difficult for the consumer to fully understand what the labels and certifications mean in most cases. Some VOC labels or certification programs are based on the VOCs emitted from the product into the indoor environment and possible related health impacts.

However, some are based on the content of VOCs that are regulated to control the formation of photochemical smog outdoors. Therefore VOC labels and certification programs may not properly assess all of the VOCs emitted from the product, including some chemical compounds that may be relevant for indoor air quality. Reducing the concentration of VOCs indoors and outdoors is an important health and environmental goal.

However, it is important to understand that there are VOCs of concern indoors and outdoors that do not impact photochemical oxidation and therefore are not regulated by EPA 42 U.

It is important to make and understand this distinction when advocating or using strategies to improve indoor air quality. For indoor air quality, ALL organic chemical compounds whose compositions give them the potential to evaporate under normal atmospheric conditions are considered VOCs and should be considered in any assessment of indoor air quality impacts.

Skip to main content. Contact Us. Technical Overview of Volatile Organic Compounds. Outdoors, VOCs are volatized or released into the air mostly during manufacture or use of everyday products and materials. General Definition and Classifications Volatile organic compounds VOC means any compound of carbon, excluding carbon monoxide, carbon dioxide, carbonic acid, metallic carbides or carbonates and ammonium carbonate, which participates in atmospheric photochemical reactions, except those designated by EPA as having negligible photochemical reactivity 2.

Classifications of VOCs When discussing indoor environments, all organic chemical compounds that can volatize under normal indoor atmospheric conditions of temperature and pressure are VOCs. Conclusion Reducing the concentration of VOCs indoors and outdoors is an important health and environmental goal. References An organic compound is any of a large class of chemical compounds whose molecules contain carbon.

For historical reasons, a few types of compounds such as carbonates, simple oxides of carbon and cyanides, as well as the allotropes of carbon, are considered inorganic. The division between "organic" and "inorganic" carbon compounds is useful, but may be considered somewhat arbitrary. Normal indoor atmospheric conditions of temperature and pressure used here refers to the range of conditions usually found in buildings occupied by people.