What is a three-electron bond

O2
N2
H2
oxygen
nitrogen
hydrogen
 

The gas oxygen is always made up of diatomic molecules. This phenomenon also occurs with other gases, such as nitrogen or hydrogen. The cause is to be found in the structure of the atoms: If the difference in electronegativity between two non-metal atoms is less than 1.7, they are happy to go one Electron pair binding a. The bond will too Atomic bond or covalent binmanure called. If the difference is greater, ionic bonding is preferred. The difference value 1.7 is only a rough guide, it also depends on other factors. In an electron pair bond, the valence electrons are shared. Example: Two hydrogen atoms form a molecule by sharing their single valence electron. In this way they both achieve the noble gas configuration of helium, i.e. two electrons in a "filled" shell:
 

 
The shared pair of electrons is represented in Lewis notation by a line or by two dots. In contrast to the empirical formula, the structural formula H-H shows H.2 the way the hydrogen atoms are linked together in a molecule. Diatomic molecules form hydrogen and nitrogen, for example, as well as the chalcogens and the halogens. As with the oxygen molecule, two binding partners can also be linked to one another by two electron pair bonds. It is then aDouble bond. At Triple bonds atoms are linked by three electron pair bonds.
 

 
 
Polar electron pair bond
 
If the difference in electronegativity between the two reactants is smaller than 1.7, but still relatively high, then the more electronegative partner pulls the shared electrons closer to it. This creates a polar electron pair bond in the water molecule.
 
Electronegativity hydrogen 2,20
Electronegativity oxygen
3,44
difference1,24

Polar molecules can be drawn at an angle. In the water molecule, the bond angle of the two OH bonds is 104.45 °. A wedge indicates that the more electronegative oxygen atom in the water molecule pulls the binding electrons closer to it.

   
 

This effect is also called inductive effectdesignated. The oxygen atom receives a negative charge, while the hydrogen atoms receive a positive charge. The water molecule is thus polar, which causes an increase in the boiling temperature if a molecule similar to the H is used2S-molecule uses for comparison: hydrogen sulfide is gaseous at room temperature. For the chemist this is polarity, the charge shift in groups of atoms or molecules, of importance when he wants to mix two polar solvents such as water and ethanol.