Metallic Bonds

1. Metallic Bonds

2. Metals don’t bond ionically • For lattices • Don’t share or lose e- like covalent or ionic bonds

3. Electron Sea Model • All metal atoms in a metallic solid contribute their valence e- to form a “sea” of e- • These e- move easily and freely because they are not tied to a specific atom • Delocalized electrons • Metallic cation is formed All empty space is evenly distributed v.e-

4. Metallic Bonds • The attraction of a metallic cation for delocalized electrons • This accounts for a lot of theproperties of metals • Range of melting points • Malleability • Ductile • Durable • Hard to remove metallic cation because of the strong e- attraction • Mobile e- • Explains why they are good conductors

5. Metallic Bonds • Transition metals tend to be harder due to “d” sublevel electrons • More e- = more attraction • Alkali metals are softer because they contain only “s” sublevel (1 sublevel) • Less e- = less attraction

6. Alloys • Mixture of elements (usually metals) that has metallic properties • Substitutional alloy – atoms of original metallic solid replaced by other metal atoms of similar size • Sterling silver  silver is replaced with Cu atoms • Interstitial alloy – small holes (interstices) in a metallic crystal that are filled with smaller atoms • Like pouring sand in a bucket of gravel • Ex. Carbon steel • Holes in iron are filled with carbon which strengthens the iron