Types of solids and properties of crystalline solids

Solids:

solids are substance s which has rigid, have definite shape and definite volume 

Typeses of Solids:

There are three types of solid 

crystalline

polycrystalline

amorphous solids

crystalline Solids:

This is the substance in which molecules and atoms  have a definite shape, arrangeed in definite three dimensional manner.

whole volume -periodic

NaCl 

                       

Amorphous solids.

this re the solids in which molecules and atoms ,ions do not have regular arrangement.

example of amorphous solids:

rubber, plastic, glue, glass.

Many crystalline solids converted to amorphous solids by cooling them rapidly after melting.

amorphous solids do not have sharp melting points.they have small range of regularity but large range of orderly arrangement in amorphous solids do not exist 

non periodic

poly crystalline:

composed of many crystallite of varying shape and orientation.

each grain -periodic

Properties/characteristics of crystalline solids.

Melting points:

crystalline can be identified by their sharp melting points.

cleavage planes:

 whenever crystalline solids  broken down they do so along definit planes called cleavage planes.

Anisotropy

Depending on the direction some crytstals show variation in physical properties.

such properties called anisotropic properties and phenomenon known as anisotropy.

refractive index, coefficient of thermal expansion, thermal and electrical Conductivity are also sometimes anisotropic in natureof some Crystals.

Example:

graphite electrical Conductivity is different in one direction them othet.

symmetry

 When crystal is rotated by 360° along its axis the repetition of faces, angles or edges is called symmetry.

Isomorphism:

Two crystalline substance exist insome crystalline form.

this substances are called ismorphs of each other.depemd upon number of atoms their way of combination not on the chemical nature of atoms On different compounds ratio of atoms is such that isomorphism is possible but their chemical properties are different.

Example Zn, cd 

crystalline form: hexagonal

atomic ratio:. 1:1

Habitat of crystal.

when saturated solution is cooled or low cooling of the liquid crystal take place crystals are obtained.

the shaoe in which crystal usually grows is the habitat of crystal s.

polymorphism:

when one compund exist in more then one form. this compound is known as polymorphic snd phenomenon is called polymorphism.

this have different chemical properties but sam chemical properties.

Transition of temperature:

this is the temperature at which the two crystalline form of a compound exist in equilibrium with each other. at this temperature one crystalline form of substance changes to another form.

Allotropy:

the element thaexistsst in more than one crystalline form is known as allotropy and the element is called allotropic forms or allotropes.

Examples:

Sulfur 

crystalline form: rhombic, monoclinic

Questions:

Cleavage of crystal s is itself anisotropic behavior.

what is the habitat of a crystal?

Difference between amorphous, crystalline, polycrystalline solids.