How do substances change after a chemical reaction

The atoms re orient themselves after a chemical reaction

Explanation:

In nature all the chemical substance cannot exists in their atomic form. They can exists freely only in molecular form. In order to do so these atoms of an element either form group among themselves or with some other elements thereby leading to a chemical reaction.  

For example – a single atom of oxygen O2- is unstable in the nature and thus it react with itself to form O2 molecule. The two oxygen atom forms a covalent bond between them thereby restructuring its orientation.  

Like wise all other chemical element also align themselves into a new structure in order to form a new compound after a chemical reaction.  

when the displaced particles are perpendicular to the direction the wave travels, is called a transverse wave, whereas in longitudinal wave the displace practices are parallel to the direction of the wave.

in the given image:

first image shows - longitudinal wave

second image shows - transverse wave

third image shows - longitudinal wave

fourth image shows - longitudinal wave