Introduction to Bonding

Metallic Bonding: Metal-metal bonds Valence electrons are mobile, moving easily from atom to atom

Ionic Bonding: Metals and Non-Metals Metals lose electrons, become (+) ions Non-metals gain electrons, become (-) ions + and – ions hold each other tightly in place

Covalent Bonding: Non-metals Sharing Electrons A handful of non-metals (C, N, O, H) are extremely common They tend to share their valence electrons with each other to gain noble gas configurations Covalent bonded elements make molecules.

Metallic Bonding Valence Electrons are a mobile “sea” Act as “lubrication”, allowing rows of atoms to slide past each other Mobile electrons account for conductivity, malliability, ductility

Metallugy The development of metallurgy has led to the rise and fall of civilizations, technological development

Important Metals

Properties of Metals Good conductors – mobile valence electrons Malleable – can be bent into shapes Ductile – can be drawn into wires Good conductors of heat (low specific heat) Shiny – has luster Many metals are dense, with high melting points Alloys (solutions of metals) have different properties than the pure metals

Alloys

Examples of Alloys Steel: Fe and C Stainless Steel: Fe, C and Cr Bronze: Cu and Sn Brass: Cu and Zn Pewter: Sn, Sb, Bi, Pb Dental Amalgam: Hg, Ag, Sn, Cu Lead Solder: Sn, Pb Lead-free Solder: Sn, Ag, Cu