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Naming and Formula Writing

Naming and Formula Writing. Practice, practice, practice. Compounds. Follow the Law of Definite Proportion. Have a constant composition. Two types: Ionic and Covalent (Molecular). Chemical Formulas. Shows the kind and number of atoms in the smallest piece of a substance.

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Naming and Formula Writing

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  1. Naming and Formula Writing Practice, practice, practice

  2. Compounds • Follow the Law of Definite Proportion. • Have a constant composition. • Two types: Ionic and Covalent (Molecular)

  3. Chemical Formulas • Shows the kind and number of atoms in the smallest piece of a substance. • Molecular formula- number and kinds of atoms in a molecule. • CO2 • C6H12O6

  4. Two Types of Compounds Ionic Compounds • Made of cations and anions. • Metals and nonmetals, generally • The electrons lost by the cation are gained by the anion. • The cation and anions surround each other. • Smallest piece is a FORMULA UNIT.

  5. Naming Binary Ionic Compounds • Binary Compounds - 2 elements. • Ionic - a cation and an anion. • To write the names: name the cation and change the suffix of the anion to -ide Straightforward with Representative metals (1,2,13). • NaCl = Na+ Cl- = sodium chloride • MgBr2 = Mg+2 Br- = magnesium bromide

  6. Naming Binary Ionic Compounds • Another step in the process comes with the transition metals. • Need to figure out their charges. • The compound must be neutral. (+ and – charges must add up to zero) In these cases- use the anion to determine the charge of the cation by doing some algebra

  7. Naming Binary Ionic Compounds Example: name CuO (Cu has multiple oxidation states, so we must do some algebra) Need the charge of Cu, so look at O • O is -2, and there is one atom of O in the compound • copper must be +2 because there is only one atom of Cu, and the charges need to add to zero • Therefore, the answer is Copper (II) oxide • Name CoCl3 • Cl is -1 and there are three of them = -3 • Co must be +3 Therefore, Cobalt (III) chloride

  8. Naming Binary Ionic Compounds • Write the name of Cu2S. • Since S is -2, the Cu2 must be +2, so each one is +1. Therefore, copper (I) sulfide • Fe2O3 • Each O is -2 3 x -2 = -6 • 3 Fe must = +6, so each is +2. Therefore, iron (III) oxide

  9. Naming Binary Ionic Compounds • Write the names of the following • KCl • Na3N • CrN • Sc3P2 • PbO • PbO2 • Na2Se

  10. KEY KCl potassium chloride Na3N sodium nitride CrN chromium (III) nitride Sc3P2scandium phosphide PbO lead (II) oxide PbO2 lead (IV) oxide Na2Se sodium selenide

  11. Ternary Ionic Compounds • Will have polyatomic ions • At least three elements • name the ions • NaNO3 • CaSO4 • CuSO3 • (NH4)2O

  12. Ternary Ionic Compounds • LiCN • Fe(OH)3 • (NH4)2CO3 • NiPO4

  13. Ternary Compound Key LiCN lithium cyanide Fe(OH)3 iron (III) hydroxide (NH4)2CO3ammonium carbonate NiPO4nickel (III) phosphate

  14. Writing Formulas • The algebraic sum of the charges must add up to zero. • Get charges on ions. • Cations from PT or Table E • Anions from PT or Table E. • Balance the charges by adding subscript, which act as multipliers for the charges • Put polyatomics in parenthesis with a subscript if there is more than one

  15. Writing Formulas • Write the formula for calcium chloride. • Calcium is Ca+2 • Chloride is Cl-1 • Ca+2 Cl-1 would have a +1 charge. • Need another Cl-1 • Ca+2 Cl2-1 the formula is CaCl2

  16. Write the formulas for these • Lithium sulfide • tin (II) oxide • tin (IV) oxide • Magnesium fluoride • Copper (II) sulfate • Iron (III) phosphide • gallium nitrate • Iron (III) sulfide

  17. Key Lithium sulfide LiS2 tin (II) oxide SnO tin (IV) oxide SnO2 Magnesium fluoride MgF2 Copper (II) sulfate CuSO4 Iron (III) phosphide FeP gallium nitrate Ga(NO3 )3 Iron (III) sulfide Fe2S3

  18. Write the formulas for these • Ammonium chloride • ammonium sulfide • barium nitrate

  19. Key Ammonium chloride NH4Cl ammonium sulfide (NH4)2S barium nitrate Ba(NO3)2

  20. Things to look for • If cations have (), the number indicated by the Roman numeral is their charge. • If anions end in -ide they are probably from the periodic table (binary) • If anion ends in -ate or -ite it is polyatomic – there are exceptions on Table E. Three of them end in –ide. Can you find them?

  21. Part 2: Covalent Compounds Molecular (Covalent) compounds • Made of molecules. • Made by joining nonmetal atoms together into molecules.

  22. Molecular compounds • made of just nonmetals • smallest piece is a molecule • Molecular compounds name tells you the number of atoms. • Uses prefixes to tell you the number of each type of element

  23. Prefixes • 1 mono- • 2 di- • 3 tri- • 4 tetra- • 5 penta- • 6 hexa- • 7 hepta- • 8 octa-

  24. Prefixes • 9 nona- • 10 deca- • To write the name write two words

  25. Prefixes • 9 nona- • 10 deca- • To write the name write two words Prefix name Prefix name -ide

  26. Prefixes • 9 nona- • 10 deca- • To write the name write two words • One exception is we don’t write mono- if there is only one of the first element. Prefix name Prefix name -ide

  27. Prefixes • 9 nona- • 10 deca- • To write the name write two words • One exception is we don’t write mono- if there is only one of the first element. • Be careful with double vowels- listen to the word when deciding whether or not to use it Prefix name Prefix name -ide

  28. Name These • N2O • NO2 • Cl2O7 • CBr4 • CO2

  29. Key N2O dinitrogen monoxide NO2 nitrogen dioxide Cl2O7 dichlorine heptoxide CBr4 carbon tetrabromide CO2 carbon dioxide

  30. Write formulas for these • diphosphorus pentoxide • tetraiodine nonoxide • sulfur hexaflouride • nitrogen trioxide • Carbon tetrahydride • phosphorus trifluoride • aluminum chloride

  31. Key diphosphoruspentoxide P2O5 tetraiodidenonoxide I4O9 sulfur hexaflouride SF6 nitrogen trioxide NO3 Carbon tetrahydride CH4 phosphorus trifluoride PF3

  32. Summary: Ionic Molecular Smallest piece Formula Unit Molecule Types of elements Metal and Nonmetal Nonmetals Solid, liquid or gas State solid Melting Point High >300ºC Low <300ºC

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