solids and liquids the microstructure of solids. 2 16.2 the microstructure of solids which one of...

Solids and Liquids

The Microstructure

of Solids

2 16.2 The Microstructure of Solids

Which one of these is not a crystal?


Glass is not a crystal but an amorphous solid!


Condensed matter:Atoms or molecules are closely packed and interact with each other

Atoms or molecules do not interact with each other, except for collisions


Fixed volume

No

Yes

Yes

Fixed shape

No

No

Yes


Microstructures

microstructrure: the spatial arrangement of atoms and molecules in matter.

Solids have one of two possible microstructures

Amorphous solidNo repeating pattern,or long-range order

Crystalline solidOrdered pattern,

like bricks in a wall


Microstructures





Glasses and most plastics are amorphous solids


Microstructures





Glasses and most plastics are amorphous solids

Crystalline solids include minerals,

gemstones, metals and even

some plastics


Crystals

Crystal structures describe:

- the distance between atoms or molecules

- bond angles between atoms or molecules

The salt in your salt shaker is made of little cubic crystals!

NaCl crystal


Water molecules align in six-sided rings

The microscopic arrangement of molecules in

a crystalline solid can show up in the shape of an object!

Snowflakes have six-way symmetry

Crystals


Amorphous solids

A-morph-ous

“without” “shape”

Glasses do not have an ordered structure.

Over time, they will sag or deform under their own weight

Most glasses are oxide glasses, because they are made mostly of

silicon dioxide (silica)


Amorphous solids

A-morph-ous

“without” “shape”An amorphous solid is like an “immobile” liquid.

As the temperature rises, the amorphous solid becomes softer and behaves more like a liquid.

Crystals only melt at one temperature.Glass is an amorphous solid


Amorphous solids

Some solids are metallic glasses

By cooling down a metal very, very fast, you can freeze its atoms into a glass.

Fancy golf club have heads made of metallic glass, because they transmit energy very well


Crystal structures

A crystal structure describes exactly the 3D repeating

pattern of atoms and molecules

Some crystals are square (table salt),

some are hexagonal (quartz and snowflakes)


Crystal structures

Bravais lattices: fourteen groups of crystal structures used to help group the many different types of crystal structures.


Crystal structures

Calcite, a rhombohedral crystal

If they are undisturbed during cooling, crytalline materials tend to

form solids along the same geometry as their structure


Crystal defects

Did you know that the

beautiful colors in

gemstones come from

crystal defects?

Ruby

Sapphire

Both sapphires and rubies are

crystals of aluminum oxide

(Al2O3) that contain different types

and amounts of impurities


Crystal defects

Crystals are 3-D structures,

so defects can occur in up to

three dimensions

Defects in a crystal structure

affect the properties of the crystal


Crystal defects

0-D defects1-D defects

2-D defects

Point defects (0-D) occur when one atom is different from the rest of the crystal

Vacancy:an atom is missing

from the crystal structure

Interstitial:an extra atom is wedged in

between others

Substitutional:a different type of atom

or molecule from the rest of the crystal

structure is present


Crystal defects

0-D defects1-D defects

2-D defects

The color of ruby comes from

chromium (Cr) substitutional defects

Substitutional:a different type of atom

or molecule from the rest of the crystal

structure is present

Ruby

Al2O3

Chromium atom

solids and liquids the microstructure of solids. 2 16.2 the microstructure of solids which one of...

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crystal structurescalcite

d repeating pattern

crystal structureinterstitial

groups of crystal structures

d structures

spatial arrangement

molecules bond angles

nacl crystalwater molecules