Transcript 8.4 Metallic Bonds and Properties of Metals

Metallic Bonds and
Properties of Metals
Metals
• Metals are made up of closely
packed cations surrounded by
electrons, rather than neutral
atoms or ions
• Outer electron clouds of the
metal ions overlap
• Electron sea model – metals in a solid contribute
their valence electrons to form a “sea of electrons”
– Valence electrons are not held by any specific atom and
can move easily from one atom to the next
• Delocalized electrons –are free to move in the “sea
of electrons”
Metallic Bond
• Definition: The attraction of the delocalized
electrons for the positively charged metal ions
• Metal bonded to metal
• Each ion is bonded to all neighboring cations
by the “sea” of valence electrons
Properties of Metals
• In general, metals have moderately high
melting and boiling points
• Good conductors of heat and electricity
• Malleable and Ductile
– Mobile electrons can easily be pushed or pulled
past each other
Structure of Metals
• Metal atoms are arranged in very compact
and orderly patterns
• Metals that contain just one kind of atom are
among the simplest forms of all crystalline
solids
Metal Alloys
• Alloy is a mixture of two or more elements (at
least one must be a metal)
• Alloy has metallic properties often superior to
those of their component elements
-Bronze: copper + tin
-Steel: iron + carbon + other metals
-Sterling silver: silver + copper
Zn
Brass though
a magnifier
Cu
Brass at the
atomic level