General Properties of Covalent Compounds

We and other animals produce their own scents. These are covalent molecules called pheromones chemicals used to attract or repel people of the opposite sex. Small quantities are produced and can be blown over long distances. Even in very dilute quantities their smell can be picked up. Perfume manufacturers try to copy these smells when making up scents, e.g. Musk for men . Hospital smells are really covalent compounds floating in the air and these attack our noses. 

The horrible smells from rotting materials or sewage are also covalent molecules floating in the air. Where there is a smell there are covalent molecules floating around. 

1 Some general physical properties of covalent molecules 

Different covalent compounds have their own characteristically shaped molecules with bonds directed at set angles. Some covalent molecules have shapes that lock onto the nerve endings in our nose and produce an electrical signal to our brains. We say that these have a smell . Perfumes, after-shave lotions and scents all contain covalent molecules that produce characteristic smells. So do the less pleasant smells. 

Covalent bonds between atoms inside a molecule are very strong and a large amount of energy has to be put in to break them, such as burning or strong heat. However, the attraction between one covalent molecule and its neighbour is usually quite weak. 

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What are three general properties of covalent compounds How are these properties related to the submicroscopic structure of the compounds ... 

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