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Chemical Nomenclature the naming and writing of chemical formulae

Chemical Nomenclature the naming and writing of chemical formulae. Masterton 2011. The system of chemical nomenclature is chosen by the International Union of Pure and Applied Chemistry ( ______________________ ). provides information on the composition of every compound

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Chemical Nomenclature the naming and writing of chemical formulae

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  1. Chemical Nomenclaturethe naming and writing of chemical formulae Masterton 2011

  2. The system of chemical nomenclature is chosen by the International Union of Pure and Applied Chemistry (______________________). • provides information on the composition of every compound Covalent Compounds • Chemical formulas represent how many of each type of __________are in each _________________. i.e. CO2 – each molecule of carbon dioxide has 1 carbon atom and 2 oxygen atoms. Ionic Compounds • Chemical formulas represent the ratio of ions in a ___________________ of the compound. i.e. LiCl – lithium and chlorine ions are present in a 1:1 ratio.

  3. Valence numbers • Represent an elements _____________________ ___________(# outer electrons) • Can be predicted by the ________ _________and the PT • Some elements have more than one possible valence number. • _ Covalent Compounds • Valence numbers indicate how many _____________ the atoms contribute to the covalent bond(s). i.e. C valence # = 4 O valence # = 2 Ionic Compounds • Valence numbers indicate the ________________ on the ions that are formed. i.e. Li valence # = 1+ Clvalence # = 1-

  4. Diatomic Gases

  5. Binary Compounds • 2 elements • less electronegative element maintains name • more electronegative element ending changes to –ide • compounds with a metal and a non-metal (ionic cpds) • Write the symbols of each element. The element with the positive valence goes first. • Mark the valence of each element. • Use the “criss cross rule” to form subscripts. • Check the subscripts any subscript of 1 can be removed divide the subscripts by the highest common factor if possible

  6. examples

  7. Polyatomic ions Polyatomic ions are ______________________________(covalently bonded group of atoms that possess a net charge) that form cations and anions. Oxyanions– polyatomic ions containing oxygen. Many combine with H to form corresponding acids (called ________________________. When writing the formulas of compounds containing polyatomic ions, follow exactly the steps as outlined for binary compounds. They behave as a single unit and the charge of the entire molecule is the valence number. When naming, the positive ion goes first then the negative ion. The ending of the polyatomic anion does ____________ e.g. calcium carbonate is calcium ion and a carbonate ion.

  8. Binary compounds continued • compounds where an element has 2 or more possible valences • The compound name must be modified to identify the ______________ of the element involved. Stock method • The name of the first element remains unchanged • Use a ____________________to represent the valence of the first element • Second element changes to –ide

  9. Alternative Method • The Latin root is used if it is different: Iron : Copper : Lead : Tin : • Suffix of first element changes:- • Lower valence possible –ous • Higher valence possible –ic • Second element changes to -ide

  10. Mercury (I) Mercurous • Mercury (II) Mercuric • Copper (I) Cuprous • Copper (II) Cupric • Lead (II) Plumbous • Lead (IV) Plumbic • Tin (II) Stannic • Tin (IV) Stannous

  11. c) binary compounds with two non-metals (covalent cpds) • prefixes are added to the both the elements. Mono- can be omitted if there is only one of the first element.

  12. Determining the valence using the zero sum rule i.e. to find the valence of the lead in PbO2 • the valence of O is 2- • the “total valence” of O in the cpd is 2 x 2- = 4- • the sum of the total valences in a compound must be 0 • the valence of lead is therefore 4+ (4+ + 4- = 0)

  13. Hydrates • substances that have water molecules present __________________ with their structure • not part of the substance • can be ___________________ • number of water molecules normally associated to the molecule/formula unit is written after the name/formula as follows. Eg.

  14. Binary Acids • Certain gases containing H atom(s) attached to 1 other element dissolve in aqueous solutions to form acids. • Will have the same formula (with (aq) after as subscript) • Naming : ______________________

  15. Ternary acids (oxy-acids) • Combinations of H with an oxyanion. • Polyatomic ions oxyacids worksheet here.... • Hydrogen .....ate .........-ic acid • Hydrogen .....ite .........- ous acid

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