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CHEMICAL NAMES & FORMULAS

CHEMICAL NAMES & FORMULAS. To describe the atomic makeup of compounds, chemists use systematic methods for naming compounds and writing formulas. Chemical Formulas. Subscript directly behind an atom applies to that atom only. H 2 O

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CHEMICAL NAMES & FORMULAS

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  1. CHEMICAL NAMES & FORMULAS To describe the atomic makeup of compounds, chemists use systematic methods for naming compounds and writing formulas.

  2. Chemical Formulas • Subscript directly behind an atom applies to that atom only. H2O • Subscripts outside of parentheses applies to all atoms inside the parentheses. Al2(SO4)3

  3. Monatomic Ions • Ions formed from a single atom. • Written as element symbol w/charge as superscript. • Monatomic cations (+) • simply element’s name. • Monatomic anions (-) • ending of element’s name is dropped. • ending –ide is added.

  4. Examples of Monatomic Ions • Write formulas for the following monatomic ions: Lithium Nitride Bromide Iron (II) • Write names for the following monatomic ions: Ba2+ Sn4+ S2- Cl- Mg2+ Cu2+

  5. Binary Ionic Compounds • Composed of 2 different elements. Total (+) and (-) charges must be equal. • Magnesium Flouride Mg2++ F- = MgF2 • Must have 2 (-) F’s to equal (+) 2 charge of Mg. • Charges Crossover. • To name combine names of cation and anion with cation being first. • ZnS Zinc Sulfide

  6. Binary Ionic Compound Examples • Write the formula for the binary ionic compounds formed between the following elements: Zinc & Iodine Zinc & Sulfur Sodium & Oxygen Calcium & Nitrogen • Name the binary ionic compounds indicated by the following formulas: AgCl CaBr2 BaO ZnO SrF2 CaCl2

  7. Stock System of Nomenclature • System used to distinguish between cations of elements that form more than one cation. Uses Roman Numerals. • CuCl2 Copper (II) Chloride

  8. Examples of Stock System of Nomenclature • Write the formula and give the name of the compounds formed between the ions: Cu2+ & Br- Fe3+ & O2- • Give the names for the following compounds: CuO CoF3 SnI4 FeS

  9. Polyatomic Ions • Most Common -ate • 1 Less O -ite • 2 Less O’s hypo- • 1 More O per-

  10. Compounds Containing Polyatomic Ions • Same as Binary Ionic Compounds • Name of Cation given 1st, Name of Anion 2nd. • When Writing formula, put parentheses around anion if more than one is present in the compound.

  11. Examples of Compounds Containing Polyatomic Ions • Write the formula for the following: Tin (IV) Sulfate Calcium Nitrite Sodium Iodide Copper (II) Sulfate • Give the name for the following compounds: Ag2O Ca(OH)2 KClO3 NH4OH KClO FeCrO4

  12. Naming Binary Molecular Compounds • Unlike ionic compounds, molecular compounds are composed of individual covalently bonded units. • Scientists use 2 systems to name these compounds, the 1st uses prefixes.

  13. Rules for the Prefix System • The less-electronegative element is given 1st. It is given a prefix only if it contributes more than 1 molecule. • 2nd element is named by: • Prefix indicating # of atoms • Root of the element • The ending –ide • When a prefix is used and the root begins w/a vowel, the o or a of the prefix is dropped.

  14. General Electronegativity Order C, P, N, H, S, I, Br, Cl, O, F Mono is normally omitted on 2nd element.

  15. Binary Molecular Compound Examples • Name the following Binary Molecular Compounds: SO3 ICl3 PBr5 • Write formulas for the following compounds: • Carbon Tetraiodide • Phosphorus Trichloride • Dinitrogen Trioxide

  16. Oxidation Numbers • Used in New System – Stock System • Same as Stock System used for Binary Ionic Compounds. • Roman Numeral is used for Oxidation Number of 1st element in a compound. 2nd element is named with name ending in –ide.

  17. Assignment Page 236 (#’s: 27, 28, & 29)

  18. Using Chemical Formulas

  19. Formula Mass • Sum of all the average atomic masses of all the atoms represented in a formula unit. • Round to 2 decimal places.

  20. Average Atomic Mass H: 1.01 amu Average Atomic Mass O: 16.00 amu 2H atoms X 1.10amu/H atom = 2.02 amu 1O atom X 16.00amu/O atom = 16.00 amu Average Atomic Mass H2O: 2.02 amu + 16.00 amu = 18.02 amu H2O Find the Formula Mass for each of the following: Potassium Chlorate Sulfuric Acid Calcium Nitrate Phosphate Ion Magnesium Chloride Calculating Formula Mass

  21. Assignment Page 236 (# 30)

  22. Molar Mass

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