lattice

Examples of lattice in the following topics:

• Lattice Energy

  • Lattice energy is a measure of the bond strength in an ionic compound.
  • Lattice energy is an estimate of the bond strength in ionic compounds.
  • as the charge of the ions increases, the lattice energy increases
  • as the size of the ions increases, the lattice energy decreases
  • This tutorial covers lattice energy and how to compare the relative lattice energies of different ionic compounds.

• Crystal Structure: Packing Spheres

  • Consider the arrangement of spheres within a lattice to form a view of the structure and complexity of crystalline materials.
  • Crystalline materials are so highly ordered that a crystal lattice arises from repetitions along all three spatial dimensions of the same pattern.
  • The crystal lattice represents the three-dimensional structure of the crystal's atomic/molecular components.
  • The structure seen within the crystalline lattice of a material can be described in a number of ways.
  • In principle, one can reconstruct the structure of an entire crystal by repeating the unit cell so as to create a three-dimensional lattice.

• Solutions and Heats of Hydration

  • The attractive interactions between ionic molecules are called the lattice energy, and they must be overcome for a solution to form.
  • The greater the value of a compound's lattice energy, the greater the force required to overcome coulombic attraction.
  • In fact, some compounds are strictly insoluble due to their high lattice energies that cannot be overcome to form a solution.
  • A hot solution results when the heat of hydration is much greater than the lattice energy of the solute.
  • Predict whether a given ionic solid will dissolve in water given the lattice energy and heat of hydration

• Ionic Crystals

  • The arrangement of ions in a regular, geometric structure is called a crystal lattice.
  • The exact arrangement of ions in a lattice varies according to the size of the ions in the crystal.
  • The resulting crystal lattice is of a type known as "simple cubic," meaning that the lattice points are equally spaced in all three dimensions and all cell angles are 90°.
  • The CsCl lattice therefore assumes a different arrangement.
  • In CsCl, metal ions are shifted into the center of each cubic element of the Cl–-ion lattice.

• Bonding in Metals: The Electron Sea Model

  • Metallic bonding may be described as the sharing of free electrons among a lattice of positively charged metal ions.
  • Metallic bonding may be described as the sharing of free electrons among a lattice of positively charged metal ions.

• Metallic Crystals

  • Understood as the sharing of "free" electrons among a lattice of positively charged ions (cations), metallic bonding is sometimes compared to the bonding of molten salts; however, this simplistic view holds true for very few metals.
  • The strength of a metal derives from the electrostatic attraction between the lattice of positive ions and the "sea" of valence electrons in which they are immersed.
  • The high density of most metals is due to the tightly packed crystal lattice of the metallic structure.
  • In metals, the charge carriers are the electrons, and because they move freely through the lattice, metals are highly conductive.
  • Electrical conductivity, as well as the electrons' contribution to the heat capacity and heat conductivity of metals, can be calculated from the free electron model, which does not take the detailed structure of the ion lattice into account.

• Formulas of Ionic Compounds

  • On a macroscopic scale, ionic compounds, such as sodium chloride (NaCl), form a crystalline lattice and are solids at normal temperatures and pressures.

• Crystal Structure: Closest Packing

  • These cells are periodically arranged to give rise to a crystal's lattice structure.
  • This section considers how the packing of atoms within unit cells contributes to a crystalline solid's lattice structure.
  • An understanding of atomic packing in a unit cell and crystal lattice can give insight to the physical, chemical, electrical, and mechanical properties of a given crystalline material.

• Doping: Connectivity of Semiconductors

  • In the atomic lattice of a substance, there is a set of filled atomic energy "bands" with a full complement of electrons, and a set of higher energy unfilled "bands" which have no electrons.
  • Electrons in the conduction band are free to move about in the lattice and can conduct current.
  • When a p-type dopant is incorporated into the atomic lattice of a semiconductor, it is able to host electrons from the conduction band, allowing the easy formation of positive holes.
  • When this occurs, an atom of dopant replaces an atom of silicon in the lattice, and therefore an extra valence electron is introduced into the structure.
  • When just a few atoms of the dopant replace silicon atoms in the lattice, an n-type semiconductor is created.

• Boiling & Melting Points

  • The distance between molecules in a crystal lattice is small and regular, with intermolecular forces serving to constrain the motion of the molecules more severely than in the liquid state.
  • Molecular size is important, but shape is also critical, since individual molecules need to fit together cooperatively for the attractive lattice forces to be large.