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2.4 Names and Formulae of Inorganic Compounds. Binary Ionic Compounds Multivalent Ions Polyatomic Ions Binary Molecular Compounds Hydrates Acids. 2.4 Names and Formulae of Inorganic Compounds. Binary Ionic Compounds.
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2.4 Names and Formulae of Inorganic Compounds • Binary Ionic Compounds • Multivalent Ions • Polyatomic Ions • Binary Molecular Compounds • Hydrates • Acids
2.4 Names and Formulae of Inorganic Compounds Binary Ionic Compounds The name of any ionic compound is simply the name of its constituent metal ion followed by the name of its constituent non-metal ion. All compounds are neutral. Ions always associate together in a ratio that results in their charges cancelling to form neutral compounds. e.g. 2Al3+ + 3S2-→ Al2S3 6+ + 6− = 0 text pages 96-97
2.4 Names and Formulae of Inorganic Compounds Multivalent Ions Multivalent elements have more than one form of stable ion. e.g. Fe2+ is the iron(II) ion Fe3+ is the iron(III) ion so Iron(II) chloride is FeCl2 Iron(III) chloride is FeCl3 text pages 97-98
2.4 Names and Formulae of Inorganic Compounds Polyatomic Ions A polyatomic ion is a charged group of covalently bonded atoms. e.g. NO3-is the nitrate ion SO42-is the sulphate ion so Calcium nitrate is Ca(NO3)2 Calcium sulphate is CaSO4 text pages 98-100
2.4 Names and Formulae of Inorganic Compounds Binary Molecular Compounds The name of a molecular compound uses a prefix code that provides its formula. The prefixes used are: 1. mono- 4. tetra- 7. hepta- 10. deca- 2. di- 5. penta- 8. octa- 3. tri- 6. hexa- 9. nona- e.g. Carbon dioxide is CO2 text pages 100-101
2.4 Names and Formulae of Inorganic Compounds Hydrates Hydrates are salts that have incorporated water molecules in a fixed ratio and pattern into their ionic crystal lattice. The same prefixes used for naming molecules precede the term –hydrate to provide the ratio of water molecules to ions in the crystal: 1. mono- 4. tetra- 7. hepta- 10. deca- 2. di- 5. penta- 8. octa- 3. tri- 6. hexa- 9. nona- e.g. Cobalt chloride hexahydrate is CoCl2∙ 6H2O text pages 101-102
2.4 Names and Formulae of Inorganic Compounds Hydrates Anhydrous salts do not have water incorporated into their crystal structure, i.e. they are not hydrates. Some anhydrous salts are hygroscopic which means they can absorb water from the air to form hydrates. Hygroscopic salts that are being used to keep the air dry in a container (a desiccator) are called desiccants. text page 101
2.4 Names and Formulae of Inorganic Compounds Acids Acids are a special type of molecular compound that can be induced to form hydrogen ions and one type of anion. The names of acids are based on the name of the anion formed. If the anion doesn’t contain oxygen then the prefix hydro- precedes the name of the anion and the suffix –ic replaces the –ide in the anion’s name, e.g. hydrogen chloride (HCl) is hydrochloric acid. If the anion does contain oxygen then the suffix -ic replaces the –ate in the anion’s name or the suffix -ous replaces the –ite in the anion’s name , e.g. hydrogen nitrate (HNO3) is nitric acid and hydrogen nitrite (HNO2) is nitrous acid. text pages 102-103