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2 O, the 2s orbital of oxygen is mixed with the premixed hydrogen orbitals, forming a new bonding (2a 1) and antibonding orbital (4a 1). Similarly, the 2p orbital (b 1) and the other premixed hydrogen 1s orbitals (b 1) are mixed to make bonding orbital 1b 1 and antibonding orbital 2b 1. The two remaining 2p orbitals are unmixed.
In chemistry, a water cluster is a discrete hydrogen bonded assembly or cluster of molecules of water. [ 1 ] [ 2 ] Many such clusters have been predicted by theoretical models ( in silico ), and some have been detected experimentally in various contexts such as ice , bulk liquid water, in the gas phase , in dilute mixtures with non-polar ...
The first theoretical study of the water dimer was an ab initio calculation published in 1968 by Morokuma and Pedersen. [10] Since then, the water dimer has been the focus of sustained interest by theoretical chemists concerned with hydrogen bonding—a search of the CAS database up to 2006 returns over 1100 related references (73 of them in 2005).
Although hydrogen bonding is a relatively weak attraction compared to the covalent bonds within the water molecule itself, it is responsible for several of the water's physical properties. These properties include its relatively high melting and boiling point temperatures: more energy is required to break the hydrogen bonds between water molecules.
An ubiquitous example of a hydrogen bond is found between water molecules. In a discrete water molecule, there are two hydrogen atoms and one oxygen atom. The simplest case is a pair of water molecules with one hydrogen bond between them, which is called the water dimer and is often used as a model system. When more molecules are present, as is ...
The bond between a water molecule and the metal ion is a dative covalent bond, with the oxygen atom donating both electrons to the bond. Each coordinated water molecule may be attached by hydrogen bonds to other water molecules. The latter are said to reside in the second coordination sphere.
The hydrogen bonds of water are around 23 kJ/mol (compared to a covalent O-H bond at 492 kJ/mol). Of this, it is estimated that 90% is attributable to electrostatics, while the remaining 10% is partially covalent. [95] These bonds are the cause of water's high surface tension [96] and capillary forces.
The bond dipole moments do not cancel, so that the molecule forms a molecular dipole with its negative pole at the oxygen and its positive pole midway between the two hydrogen atoms. In the figure each bond joins the central O atom with a negative charge (red) to an H atom with a positive charge (blue).