Review: For each substance, identify the type of solid, the type of attractive force holding the solid together, and make any comparisons about their relative melting points and electrical conductivity that can be made. I2 HCl SiC NaCl NaBr

Chemistry of Solids

Goals for today: Draw simple representations of different types of solids that illustrate important aspects of their structure Analyze models of different solid types in order to explain the properties of these substances.

Metal atoms lose their valence electrons, creating positive ions Metallic Solids: “Sea of electrons” theory The electrons are “delocalized” can flow freely between the ions

Metallic Solids: Metal ions attracted to each other via metallic bonds. The + ions are held in place by their attraction to the electrons surrounding them

Metallic Solids: Metal ions attracted to each other via metallic bonds. This attraction is usually comparable in strength to ionic or covalent bonds

Metallic Bonding

Metallic Solids: Predictable Properties Melting Point: (on your own) Generally higher, but can vary widely Mercury and gallium Electrical conduction: (on your own) Excellent conductors of electricity

Metallic Solids: Not-so Predictable Properties Thermal conduction: Good thermal conductors The delocalized electrons help to transfer kinetic energy throughout the metal quickly

Metallic Solids: Not-so Predictable Properties + - + - + Hardness: - + - + - + - + - + - + - + - + - + - +

Metallic Solids: Not-so Predictable Properties - + - + Hardness: + + - + - - - + - + + + - + - - - + - + +

Metallic Solids: Not-so Predictable Properties - + - + Hardness: + - + - - + - + + - + - - + - +

Metallic Solids: Not-so Predictable Properties Hardness: (on your own)

Metallic Solids: Not-so Predictable Properties Hardness: (on your own)

Metallic Solids: Not-so Predictable Properties Hardness: (on your own)

Metallic Solids: Not-so Predictable Properties Hardness: (on your own) The rows easily re-align, but without being repelled and breaking off

Metallic Solids: Not-so Predictable Properties Hardness: This is called malleability

Metallic Solids: Not-so Predictable Properties Easily alloyed: An alloy is a mixture of different metals 2 Types: Interstitial and Subsitution

Metallic Solids: Not-so Predictable Properties Interstitial Alloys: Smaller atoms wedge into the spaces between the metals

Metallic Solids: Not-so Predictable Properties Interstitial Alloys: The interstitial atoms get in the way and make it harder to displace the rows

Metallic Solids: Not-so Predictable Properties Interstitial Alloys: Interstitial alloys increase the hardness of the base metal

Metallic Solids: Not-so Predictable Properties Substitution Alloys: Atoms of similar size replace the original metal atoms

Metallic Solids: Not-so Predictable Properties Substitution Alloys: The properties of the alloy are a blend of the 2 separate metals