Solids- Properties

Solids- Properties

Warm-up: Why does a gas have a greater ability to compress when compared to a liquid?

Draw the relative arrangement of particles in solids, liquids, and gases

solids

• Solids according to Kinetic molecular theory have tightly packed particles that move about a fixed position

• Crystalline solids- particles are arranged in an orderly, geometric, repeating pattern

• Amorphous solids- particles are arranged randomly.

Multiple Choice

Based on your quick research is Rhodonite a crystalline or amorphous solid?

• crystalline

• amorphous

On your paper arrange the listed solids into the two classes based on your personal research

Solids

• - supercooled liquid-substances that retain certain liquid properties even at temperatures they appear to be solid

• Solids are incompressible mostly and have relatively high densities

• They also have very low diffusion rates

Open Ended

What element has the lowest density? What element has the highest density?

Open Ended

If solids are incompressible why can you compress a cork?

Crystalline Structures

• Total three-dimensional arrangement of particles of a crystal is called a crystal structure

• The smallest portion of a crystal lattice that shows the 3D pattern of the entire lattice is called a unit cell

Crystalline symmetry

• Cubic

• Tetragonal

• Hexagonal

• Trigonal

• Orthorhombic

• Monoclinic

• Triclinic

Group Project

• You will be given a crystal structure to research

• As a group you will find a solid that has that structure

• Title your- project as solid name and crystal structure

• You will draw the crystal structure and draw and color the solid.

• Provide properties of the solid (go to flinn scientific then go from their) i.e. is it flammable, melting and boiling point, formula unit(something like NaCl)

• Next, research the binding forces in the crystal and classify it as Ionic crystals, Covalent Network Crystals, Metallic Crystals, Covalent molecular crystals

• Finally, draw a diagram of the 3D atomic structure of the formula unit( the best you can)

Forces in crystals

• Ionic Crystals- positive and negative ions arrange in a regular pattern. The ions can be monoatomic or polyatomic. Normally form when Group 1 or 2 and Group 16 or 17 combine. Ionic Bonds- hard and brittle, high melting points, good insulators ( in a dissolved state they are good conductors of electricity)

• Covalent Network Crystals- each atom is covalently bonded to its nearest neighboring atom and makeup what is pretty much a giant molecule. - These include diamonds, quartz, silicon carbide and many others. These are very brittle, have high melting points and are usually non or semi conductors

Forces in Crystals

• Metallic Crystals-metal cations are surrounded by a sea of delocalized valence eleactrons that come from the metal atom and move through the whole crystal.- this explains the electrical conductivity of metal

• Covalent Molecular crystals- covalently bonded molecules are held together by intermolecular forces. Whether these are polar or non-polar these forces are much weaker than the bonds in covalent network crystals. These have low metling points, are soft, and are good insulators

Amorphous Solids

• Glass is cooled in a way that prevents crystallization. The resulting properties makes them useful for a wide range of uses

• Plastics are easily molded at high temp. and pressure

• Rubber is easily flexed but returns to its original shape if not pushed past its breaking point

• Gels return to their initial shape when deformed as well

Amorphous Solids

• Do not have long range order but do have short range order

• Dont show much distinction between solid and liquid

• Have wide melting ranges

• Do not form regular shapes when broken like crystals do