<P> The most ubiquitous and perhaps simplest example of a hydrogen bond is found between water molecules . In a discrete water molecule , there are two hydrogen atoms and one oxygen atom . Two molecules of water can form a hydrogen bond between them ; the simplest case , when only two molecules are present , is called the water dimer and is often used as a model system . When more molecules are present , as is the case with liquid water , more bonds are possible because the oxygen of one water molecule has two lone pairs of electrons , each of which can form a hydrogen bond with a hydrogen on another water molecule . This can repeat such that every water molecule is H - bonded with up to four other molecules , as shown in the figure ( two through its two lone pairs , and two through its two hydrogen atoms ) . Hydrogen bonding strongly affects the crystal structure of ice , helping to create an open hexagonal lattice . The density of ice is less than the density of water at the same temperature ; thus , the solid phase of water floats on the liquid , unlike most other substances . </P>
<P> The most ubiquitous and perhaps simplest example of a hydrogen bond is found between water molecules . In a discrete water molecule , there are two hydrogen atoms and one oxygen atom . Two molecules of water can form a hydrogen bond between them ; the simplest case , when only two molecules are present , is called the water dimer and is often used as a model system . When more molecules are present , as is the case with liquid water , more bonds are possible because the oxygen of one water molecule has two lone pairs of electrons , each of which can form a hydrogen bond with a hydrogen on another water molecule . This can repeat such that every water molecule is H - bonded with up to four other molecules , as shown in the figure ( two through its two lone pairs , and two through its two hydrogen atoms ) . Hydrogen bonding strongly affects the crystal structure of ice , helping to create an open hexagonal lattice . The density of ice is less than the density of water at the same temperature ; thus , the solid phase of water floats on the liquid , unlike most other substances . </P>
the bond which is found between water molecules such as in ice crystals is a ( n )
the bond which is found between water molecules such as in ice crystals is a ( n )
Hydrogen bonding
Hydrogen bonding