# Crystal Lattices and Unit Cells, End Centred, Formation of Lattice (For CBSE, ICSE, IAS, NET, NRA 2022)

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## Formation of Lattice

• Cubic Lattice: Cubic lattice is formed into three possible geometries of unit cells: primitive, body-centred and face centred unit cells. In a cubic lattice, all the edges are equal and the angle between their faces is that is, mutually perpendicular.
• Tetragonal Lattice: The formation of tetragonal lattice takes place in two geometries of unit cells: primitive and body centred unit cells. In a tetragonal lattice, only one edge has different length and angle between respective edges is that is, mutually perpendicular
• Orthorhombic Lattice: There are four types of orthorhombic lattice mainly: primitive, end-centred, body-centred and face centred. In orthorhombic lattice, the edge lengths are unequal in nature and the angle between respective edges is that is, mutually perpendicular
• Monoclinic Lattice: Monoclinic lattice is formed from two types of unit cells namely: primitive and end centred. Monoclinic lattice has unequal sides and two angles between the faces of the lattice are .
• Hexagonal Lattice: Hexagonal lattice is formed from only one type of unit cell that is, primitive. In hexagonal lattice, only one side and two angles are and one angle are .
• Rhombohedral Lattice: Rhombohedral Lattice is also formed from one type of unit cell that is, primitive. In Rhombohedral Lattice all the sides are equal and two angles between the faces of the rhombohedral lattice are less than .
• Triclinic Lattice: The formation of triclinic lattice also takes place from one type of unit cell that is, primitive. In triclinic lattice all the sides are unequal and none of the angles between the faces of the triclinic lattice are .

## Questions

### What is a Lattice Structure?

Answer: A lattice is an ordered set of points that define the structure of a crystal-forming particle. The lattice points identify the unit cell of a crystal. All the particles (yellow) are the same in the drawn structure.

### What is the Lattice Point in Crystals?

Answer: The points in a crystal lattice in the model crystal represent the positions of structural units (atoms, molecules or ions) . Every lattice point in the crystal has the same surroundings as the actual crystal structural units.

### What is a Lattice Point in a Unit Cell?

Answer: Unit cell corner is described by a lattice point at which the crystal contains an atom, ion, or molecule. The cubic unit cell centered on the body is the simplest repeating unit in a cubic structure centered on the body. Once again, the eight corners of the unit cell contain eight similar particles.

### How Crystal Lattice is Formed?

Answer: If one mole of an ionic compound is formed, it is the energy produced. That ensures that when the compound՚s individual ions come together to form the crystal lattice, they need less energy to remain together so that they release it and the energy released is called the energy of the lattice.

### What Causes a Crystal Lattice?

Answer: The ionic crystal consists of electrostatic attraction linking ions together. The arrangement of ions is called a crystal lattice in a regular, geometric structure. The alkali halides are examples of such crystals, including: potassium fluoride (KF)