BONDS     A bond is the chemical connection that ties atoms together. I. TYPES OF BONDS A. Ionic 1. Involves transfer of electrons to or from the outer electron shell 2. Very strong, produces brittle minerals 3. Important in formation of minerals B. Covalent 1. Involves sharing of electrons within outer shell (no electrons are gained or lost) 2. Strong bonds, produces brittle minerals C. Distinctions between ionic and covalent bonds 1. Atoms with only one shell bond from their outermost (that is, their only) shell and possess at most two electrons a. Hydrogen has one proton in its nucleus and one electron in its outermost shell b. Hydrogen bonds with another hydrogen to become stable. This combination forms a "molecule" c. H2 is common in nature, while H+ is a rarity 2. Covalent bonds share electrons while ionic bonds transfer electrons D. Metallic 1. Electrons are free to float about the metal crystalline structure 2. Electrons are not confined to one atom 3. Deals only with metals such as gold (Au) 4. Minerals with metallic bonds a. Conduct heat b. Conduct electricity c. Are malleable and ductile E. Van der Waals 1. Van der Waals bonds--Relatively weak attractive forces operating between neutral atoms or molecules due to momentary electrical polarizations caused by the distribution of electrons within their orbits 2. Minerals with Van der Waals bonds a. Graphite (sheets of carbon atoms where one surface is positively polarized and the other surface is negatively polarized) 1. Most slippery naturally occuring substance 2. High lateral strength (along sheets) 3. Good for fishing rods, tennis rackets, aircraft wings b. Talc II. RESULTS OF BONDS A. Polymorphs--same chemical composition but different crystal structures e.g. diamond and graphite B. Compound--substance composed of more than one type of atom; a group of elements 1. Copper Sulfide (CuS -> Cu+S) 2. Iron Oxide (2FeO -> 2Fe + O2) C. Molecule--smallest unit of a compound that displays the properties of that compound D. Minerals---classified by physical properties or chemical makeup 1. Naturally occuring 2. Inorganic solid 3. Unique set of physical properties 4. Specific chemical composition (or range of chemical compositions) 5. Ordered crystalline structure 6. Two main groups a. Silicates - most minerals within the Earth's crust; composed of cations bonded to silicon (Si) and oxygen (O) b. Non-silicates