TYPES AND PROPERTIES OF SOLID

TYPES AND PROPERTIES OF SOLID

Objectives

• describe the differences between amorphous and crystalline solids;

• distinguish the different types of crystalline solids.

Classes of Solids

• Amorphous solid

• Crystalline solid

The properties observed in solids like those in liquids can also be explained through the interparticle forces within them.

In solids, the particles are more attracted with one another which allows them to be in contact in fixed positions, thus occupying specific amounts of space. This explains the definite shape and volume of solids.

Also, the particles have less kinetic energy so movement of the particles is very limited, though possible, like vibrational motion about a fixed point.

An increase in the temperature of a solid brings about an increase in the kinetic energy of the particles and may cause them to move about but still within the limits of the attractive forces holding them. 

Amorphous Solid

• an amorphous - from the Greek a, without, morphé, shape, form - or non-crystalline solid is a solid that lacks the long-range order that is a characteristic of a crystal.

The word amorphous means that the solid does not always adopt the same form. Its constitute particles are randomly arranged. Examples are asphalt, rubber, glass, and plastic. These solids are the results of the melting, cooling, and solidifying of liquids before the particles can achieve internal order, (like glass) or having large molecules that are tangled together (like rubber and plastic).

Amorphous solids do not have sharp melting points, that is, melting within a narrow temperature range. Instead, they soften first and melt little by little over a wide temperature range. 

Amorphous solids include both natural and man-made materials. The most frequently cited example of an amorphous solid is glass. However, amorphous solids are common to all subsets of solids. Additional examples include thin film lubricants, metallic glasses, polymers, and gels.

Examples of amorphous solids

Crystalline Solid

The word crystal derives from the Ancient Greek word krustallos, meaning both "ice" and "rock crystal", kruos, "icy cold, frost"

It is a solid in which the constituent particles (atoms, ions, or molecules) have orderly arrangement, that is, it has regularly arranged structure units with characteristic geometric forms. Thus, crystals show regular shapes which reflect the arrangement of the particles within them. 

Crystalline solids consist of repeating, three-dimensional patterns or lattices of molecules, ions or atoms. These particles tend to maximize the spaces they occupy, creating solid, nearly incompressible structures. 

A three-dimensional lattice

Types of Crystalline Solids

Metallic Solids

Metallic solids

• composed of metal atoms bonded together by metallic bonds

• simplest type of structure since single metallic atoms are the constituent units

• easily deformed which explains why metals are malleable and ductile

• other examples of metallic solids are silver, tungsten,bronze

Ionic Solids

• Have ions as constituent particles.

• Ionic crystalline solids are comprised of positive and negative ions held together by ion-ion attraction. 

• Ionic crystalline solids are known for their high melting points and for being hard and brittle. 

• Common examples include sodium chloride (NaCl), magnesium oxide (MgO) and calcium fluoride (CaF2).

Crystal structure of NaCl

Molecular Solids

• Molecular crystalline solids are comprised of molecules, which are held together by dispersion.

• Molecular crystalline solids are fairly soft, make poor electrical and thermal conductors and have low to moderate melting points.

• Common examples include ice, sucrose, camphor, menthol and naphthalene.

Network Solids

• Network crystalline solids consist of atoms that are held together by covalent bonds

• They are incredibly hard, have high melting points and are poor conductors of heat and electricity. 

• Some of the most well-known crystalline solids— graphite, quartz, and diamonds.

Open Ended

World's Smallest Hard Drive

The crystal material in the world's smallest hard drive is made of fused quartz from an almost-pure silica. Developed in Britain, the crystal can hold up to 360 TB of data on its surface and is stable up to 1832 ⁰F.

If you were to use this hard drive, what data will you store in it? Will you depend on it to save all your life information? Why?