In chemistry, the structure of a non-metallic
element or compound, in which groups of atoms
are joined together by covalent bonds
to form a molecule
. The molecules of non-metals are often made up of two identical atoms covalently bonded together, for example: oxygen (O2
), hydrogen (H2
), and nitrogen (N2
). There are also molecular compounds
made up of different non-metal atoms bonded together, such as water (H2
O), ammonia (NH3
), and carbon dioxide (CO2
Simple molecular structures have distinctive properties. Although the covalent bonds within the molecules are very strong, the molecules are held together by relatively weak intermolecular forces. As the molecules can be parted easily, simple molecular substances are not very hard or strong and have low melting and boiling points. At room temperature, most simple molecular substances are either a gas or liquid. They do not usually dissolve in water and do not conduct electricity because they have no ions
. Simple molecular solids
, such as ice, melt easily and tend to dissolve in organic solvents.
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