What Are Ceramics?

Metals&ceramics can both be crystalline.but metals're ductile ceramics're brittle.what are the reasons of it?

• Answer:

  First you have to have understanding of their bonding. Metallic bond - Metallic bonding is the bonding within metals. It involves the delocalized sharing of free electrons among a lattice of metal atoms. These become delocalized electrons or sometimes called a Sea of Electrons surround a giant lattice of positive ions. Why is it ductile? It is ductile because the attracive forces between the free electrons and cations (positive ions) are very strong. However the cations are able to change its positions(ie change shape) but not seperated from the whole lattice structure. Ceramic on the other hand is an ionic solid. Ionic bonds are a type of chemical bond based on electrostatic forces between two oppositely-charged ions. Often ionic bonds form between metals and non-metals. take salt for example: http://www.geo.arizona.edu/xtal/geos306/9_2.jpg when the struture is changed as a result of impact (ie a piece of the block move downwards by one atom), the positive ions (Na+) changed its location, next to another Na+ ion. (same with the Cl- ion)so they repelled and causes the whole structure to fall apart (brittle).