Chemistry Basics: Oxides, Salts, Alloys, Allotropes and Metal Toxicity

Chemical Compounds and Nomenclature

Metal Oxides: Formed by the reaction of a metal with oxygen. Formula: metal + oxygen. Name: rust in some cases, or the metal oxide name.

Nonmetal Oxides: Formed by the reaction of a nonmetal with oxygen. Formula: nonmetal + oxygen. Name: mono-, di-, tri-, tetra-, penta- oxide prefixes indicate the number of atoms.

Hydroxides: Compounds containing the metal cation bonded to the hydroxide anion (OH^-). Formula: metal (OH)_n. Name: metal hydroxide.

Oxoacids: Compounds of hydrogen, oxygen and a nonmetal. Formula: H_n(nonmetal)O_m. Naming: the -ic and -ous endings and the per- and hypo- prefixes indicate the oxygen content.

Hydracids: Binary compounds of hydrogen and a nonmetal. Formula: HnonM. Name: acid with the suffix -hydric.

Salts: Formed from the reaction of a hydracid with a hydroxide, producing a salt and water. Formula: hydroxide + hydracid. Name: nonmetal suffix -uro + metal name.

Properties and Occurrence of Salt

Salt: A white, water-soluble crystalline solid. Its microscopic structure is made of cations and anions arranged in an ordered lattice.

Natural sources: Ocean water, mines, rivers, lakes and underground deposits such as rock salt (halite).

Historical use: In antiquity salt was prized as gold and used for exchange, seasoning and preservation.

Today: Used for seasoning, preservation and as a premium raw material for obtaining sodium chloride.

Importance: Regulates fluid balance, supports kidney function, regulates blood pressure and blood volume.

Crystal shape: Cubic crystals, with cube or pyramid forms at the submicroscopic level.

Monetary Metals and Terms

Terms: Matrix: metal employed as the base of currency. Law: regulation of the metal's purity, degree and defined form. Control: central bank and the mint.

Alloys

Alloys: A mixture of two or more metals, or of one metal and one nonmetal. Objective: to obtain materials with improved properties derived from their different components.

• Bronze: Regular copper with 5 to 30% tin.
• Brass: Contains 30 to 55% zinc, with copper and zinc (nickel silver adds nickel).
• Steel: Carbon and iron.
• Stainless steel: Steel with chromium and nickel or cobalt.
• Slag: Silicate waste of sodium.
• Pig iron: Iron with impurities.

Bioremediation

Bioremediation: A technology used to heal polluted soils, groundwater and different compounds.

Types:

• Biostimulation: Adding nutrients to eliminate contaminants.
• Bioaugmentation: Adding selected bacteria that multiply and degrade pollutants.

Examples: Fungi degrade petroleum; bacteria concentrate mercury; plants such as Thlaspi accumulate zinc and cadmium in soils.

Toxic Heavy Metals

Heavy metals:

• Lead: Used in paints and similar products. It accumulates in bones, kidneys and the nervous system, and causes anemia.
• Cadmium: Used in paints and tanning. Exposure causes bronchitis, infertility, prostate cancer and hypertension.
• Mercury: Used in industrial chemistry and the automotive industry. It causes damage to the central nervous system and irreversible brain damage.
• Arsenic: Used in industrial chemistry. It can become integrated into certain proteins and is found in the skin and nails. Exposure is common in some industrial workplaces.

Allotropy

Allotropy: The property by which an element holds its atoms in different spatial arrangements. Allotropes of carbon include diamond, graphite and buckminsterfullerene.

Diamond: A stable crystalline form with an infinite network of bonds. It is the hardest natural material and can only be cut by another diamond. Uses: jewelry, surgical materials and tools. Impurities: nitrogen gives a yellow color; boron gives a bluish-gray color.

Graphite: Hexagonal carbon atoms form layers stacked on top of each other, weakly bonded, so the layers can slide over one another. Uses: pencil leads and lubricants for locks.

Cooking Tips

Green vegetables should be cooked in a pot without a lid to preserve their color and nutrients.

Silicones

Silicones: Polymers formed by condensation, developed during the Second World War. They consist of silicon atoms bonded to oxygen and organic groups. Methylsilicones are formed from methyl silicon chloride.

Properties: Insulating, sealing, waterproof, chemically inert, heat stable.

Uses: Manufacture of prostheses, artificial respirators, dialysis equipment, aircraft hydraulic systems, and production of textiles, paper and ceramics.