Chapter 8 (p ) Chemistry Mr. Gilbertson

Metals consist of closely packed cations floating in a “sea of electrons”. Valence electrons are said to be “delocalized” because they are not specifically associated with any one metal atom. All of the atoms are able to share the electrons. The electrons are not bound to individual atoms.

Melting points – vary greatly Mercury – liquid at room temp Tungsten – MP 3422 o C Generally MP and BP are moderately high MP not as extreme as BP, cations are mobile so not as much energy is required to move past one another BP is higher because cations must be separated which takes much more energy

Metal cations can be pushed or pulled past each other Ductile – can be drawn into wire Malleable – can be hammered into sheets Electrons act as a lubricant, allowing cations to move past each other Durable – strong attraction to electrons

Conductivity of metals Delocalized electrons are free to move Movement of mobile electrons around cations allows an electric current to flow When electrical potential is applied to a metal electrons are forced to metals have less “resistance” Delocalized electrons move heat from one place to another much more quickly than in materials without mobile electrons

Luster – shiny when smooth and clean Caused by interaction of mobile electrons and photons of light Hardness and strength Increases with an increase in the number of delocalized electrons. Transition metals are generally harder (Cr, Fe, Ni) Alkali metals are soft (only 1 delocalized electron)

Mixtures of two or more elements, at least one of which is a metal. Made by melting, mixing, then cooling the metals. May contain non-metals like carbon.

Properties are superior to their components. Sterling silver 92.5% Ag, 7.5% Cu Harder than silver Bronze 7:1 Cu to Sn (tin)

Stainless Steel Fe 80.6%, Cr 18%, C 0.4%, Ni 1% Cast Iron -Fe 96%, C 4%

Two types of formation: Substitutional alloys Similar size atoms – replacement Interstitial alloys Different size atoms – smaller ions fill interstices (spaces between atoms)