Law of constancy of the interfacial angle:
This was discovered by Nicolas Steno in 1669 and is expressed by Steno's law of constancy of interfacial angles – the angles between corresponding crystal faces of the same mineral have the same angle.
The law of constancy of interfacial angles (or “first law of crystallography”) states that the angles between the crystal faces of a given species are constant, whatever the lateral extension of these faces and the origin of the crystal, and are characteristic of this species.
In all crystals of the same substance, the angles between corresponding faces have the same value when measured at the same temperature.
The angles between the corresponding faces of different crystals of the same chemical composition have a constant value.

The law of constancy of interfacial angles is a law in crystallography that is essential for identifying the crystal structures of various minerals. The law states that the angle at which the faces of a crystal intersect remains constant for that particular species of crystal. This can help identify the mineral crystal by measuring the angle and comparing it to known interfacial angles.
Crystals of a substance are obtained by cooling the liquid (or melt) or solution of that substance. The size of the crystals depends

Crystal forms (crystal habits) of a particular substance.

The recooling. If cooling is carried out slowly, large crystals are obtained because the particles (ions, atoms or molecules) have sufficient time to arrange themselves in the appropriate positions. Similarly, it is found that the shape of the crystals of a substance also depends on the conditions under which the crystallization takes place, that is, in the absence or presence of any other substance, etc. For example, the shapes of crystals of a particular substance are represented in figs.

However, taking into account the different sizes and shapes of crystals of the same substance, the following regularity is observed:

The angles between corresponding faces, called interfacial angles of crystals of a particular substance, are always the same. This is called the law of constancy of interfacial angles. The instrument used to measure interfacial angles is called a goniometer.

Furthermore, it is found that the shape of the crystals of a substance also depends on the conditions under which the crystallization takes place, i.e. in the presence or absence of any other substance, etc. For example, sodium chloride grows when cubes form. aqueous solution but in octahedral form, 15% aqueous urea solution.

A wide variety of forms of crystalline substances have been observed. We are therefore tempted to classify the variety of forms on some basis. Such classification is based on the symmetries exhibited by the crystals and their internal structure. In the next section, therefore, we will discuss the elements of symmetry that crystals and molecules possess.
#shorts #short #shortvideo #shortsvideo #shots

Please take the opportunity to connect and share this video with your friends and family if you find it useful.