# How is a mesh formed?

### How is a mesh formed?

A mesh is a unit of repetition per translation. It is defined by its basis vectors, which are chosen so as to form a direct triad. The problem is that for a given crystal, we can define several stitches corresponding to several possible translations.

### What is the unit cell?

Unit cell = any polyhedron whose vertices are nodes of the network, and such that the stack of polyhedra all identical to the first can fill the entire space without voids or material overlaps (Figure 10). Ex: tiles – the unit cell = small square.

### What is the geometric shape of the conventional mesh?

The conventional mesh of the network (mesh red in the face) has sides parallel to the axes of symmetry of the lattice, whereas in the mesh corresponding primitive (mesh black in the face), the two directions of symmetry are bisectors of the axes (aP and bP).

### What is the difference between a crystal and an amorphous solid?

This is the first question that to ask chemists when studying a material solid. This last is crystalline when there is an ordered arrangement of atoms. He is amorphous when the atoms that compose it are disordered.

### What is the crystal lattice shape of sodium chloride?

Structure crystalline the sodium chloride (salt) is an assembly of ions sodium Na+ and chlorine Cl– de mesh cubic. Salt is a crystal, because its atoms form a periodic and symmetrical structure.

### What is the meaning of the word mesh?

1. Constituent element of any textile surface comprising a more or less loose network of intertwined threads (knits, tulles, nets, in particular); hole formed by each loop: Fish who passes through the stitches.

### Where are the crystals?

In nature, the crystals are present in rocks as minerals. We find also crystals in living beings.

### What is the difference between a stitch and a pattern?

Mesh and pattern. The content of the mesh is repeated by translation in the 3 dimensions. The content of the mesh can be made of a repeating pattern (inside the mesh) by symmetries other than translations. The content of a mesh can consist of only one pattern (if there is no symmetry).

### What is the content of a mesh?

The content of a mesh can consist of only one pattern (if there is no symmetry). The knowledge of the pattern and the symmetries makes it possible to reconstitute the content of the cell, the knowledge of the cell makes it possible to reconstruct by translation the whole crystal.

### What is Mesh Knowledge?

For example centers, planes, axes… The content of a mesh can only consist of a pattern (if there is no symmetry). The knowledge of the pattern and the symmetries makes it possible to reconstitute the content of the cell, the knowledge of the cell makes it possible to reconstruct by translation the whole crystal.

### Who invented the mesh?

The concept of mesh was proposed by Gabriel Delafosse from the notion of “integrating molecule” introduced by René Just Haüy, who had noticed that a crystal splits into smaller crystals of the same shape as the original crystal.