Ionic+molecules

The main reference for the is topic is chapter 6 =Ionic bonds= These occur between a metal and a non metal. We often say the metal donates an electron to the nonmetal - the result is an anion and cation held strongly together by electrostatic forces. The result of these bonds are the properties ionic molecules possess - these are
 * 1) High MP and BP - the forces between the atoms are very strong,
 * 2) Hard -the forces between the atoms are very strong
 * 3) Brittle--the forces between the atoms are very strong so if the cation slides across the anion and ends up over another cation replusion occurs and hence shatering.
 * 4) Also they do not conduct electricity in the solid state - will in aqueous or molten state as the ions can travel.

Combining metals and non metals
they combine to form a 3D crystal lattices this lattice is held together strongly by electrostatic forces

Writing formula for ionic compounds
elements combine according to the valence number Eg X has a valency of 3+, Z has a valency of 3- therefore the ionic compounds formula is XZ

however when we combine X with A (which has a valency of 1+) XA 3

= Uses of ionic compounds = Make use of their properties insulators - ceramic hard - marble statues fertilisers food - salt

= Ionic crystals and metallic crystals = = ---From the free dictionary =

Understanding Ionic Crystals
As solids, ionic crystals are insulators. As Encyclopedia Britannica states: Other key features of these ionic crystals are:


 * They melt or boil only at very high temperatures. The enthalphy of these crystals (the amount of fusion and vaporization necessary to melt one mole) is as much as 100 times that of other molecular compounds.
 * They are very hard. They are so brittle because if one layer of ions must move past another, the entire arrangement is disturbed.

The crystalline structures form after the bond is created and the structure varies based on the ions which have combined.

> Some n=more information from Boundless - https://www.boundless.com/chemistry/liquids-and-solids/types-crystals/ionic-crystals/

Ions in ionic crystals are bound together by electrostatic attraction.
fig. 1=====NaCl crystal structure===== Circles represent the Na+ and Cl- ions. Each ion is surrounded by six other ions of opposite charge, (6,6) coordination. > A regular three-dimensional geometric arrangement of atoms, molecules or ions in a crystal. > A class of crystal consisting of a lattice of ions held together by their electrostatic interaction; they exhibit strong absorption of infrared radiation and have planes along which they cleave easily. > The energy required to separate the ions of an ionic solid (especially a crystal) to infinity.
 * 1) [[image:https://d3r4ecz8hnfnqf.cloudfront.net/50774400e4b0e714e3d007e0/full/nacl-struct.jpeg width="280" height="234.68879668049794"]]
 * Ions bound together by electrostatic attraction form ionic crystals, where their arrangement varies depending on ions sizes or the radius ratio (the ratio of the radii of the positive to the negative ion). A simple cubic crystal lattice has ions equally spaced in 3D at 90° angles.
 * Stability of ionic solids is dependent on lattice energy, which is released in the form of heat when two ions are brought together to form a solid. Lattice energy is the sum of all the interactions within the crystal.
 * The properties of ionic crystals reflect the strong interactions that exist between the ions.They are very poor conductors of electricity, have strong absorption of infrared radiation, and are easily cleaved. These solids tend to be quite hard and have high melting points.
 * crystal lattice
 * ionic crystal
 * lattice energy

For more information and diagrams go here http://www.tf.uni-kiel.de/matwis/amat/def_en/kap_2/basics/b2_1_6.html

http://www.seas.upenn.edu/~chem101/sschem/ionicsolids.html