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Chemical Names and Formulas

Chemical Names and Formulas. Unit 5. Counting Atoms. The subscript tells how many of that element is present. Eg: H 2 O 2 = 2 hydrogen, 2 oxygen If there is no subscript next to the symbol, it counts as “1”. Eg: NaCl = 1 sodium & 1 chlorine. Counting Atoms.

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Chemical Names and Formulas

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  1. Chemical Names and Formulas Unit 5

  2. Counting Atoms • The subscript tells how many of that element is present. • Eg: H2O2= 2 hydrogen, 2 oxygen • If there is no subscript next to the symbol, it counts as “1”. • Eg: NaCl = 1 sodium & 1 chlorine

  3. Counting Atoms • If the subscripted number is outside of the parenthesis, it is distributed to all elements within the parenthesis. • Eg: Ca(NO3)2 = NO3 x 2. • A preceeding coefficient is multiplied to all atoms in the compound. • Eg: 2NaCl = 2 sodium & 2 chlorine

  4. Counting Atoms • Calcium Carbonate: CaCO3. Ca = Calcium = 1 C = Carbon = 1 O = Oxygen = 3 5 Total atoms =

  5. Counting Atoms • Magnesium Hydroxide: Mg(OH)2. Mg = Magnesium = 1 H = Hydrogen = 2 O = Oxygen = 2 5 Total atoms =

  6. Counting Atoms • Acetic Acid: 2HC2H3O2. H = Hydrogen = 2 + 6 = 8 C = Carbon = 4 O = Oxygen = 4 16 Total atoms = • Now complete the Counting Atoms review worksheet.

  7. Chemical Formulas • The simplest compounds contain 2 elements and are called Binary. • In ionic binary compounds, a cation and an anion join together to form a neutral compound. • Ionic compounds are made from a metal and a non-metal. • IMPORTANT: ALL COMPOUNDS ARE NEUTRAL!!! Ionic Compound Cation + Anion =

  8. Chemical Formulas • Potassium Bromide = KBr • Calcium Bromide = CaBr2 • Lithium Fluoride = LiF • Lithium Oxide = Li2O • Note that the subscript has nothing to do with the name of the ionic compound.

  9. Chemical Names • Example: LiF • The element with the positive charge, cation (the metal) is written first. • This element is given its usual name, in this case, Lithium. • The second element is the anion. It’s name will be changed to end in “-ide”. Fluorine is changed to Fluoride. • The compound’s name = Lithium Fluoride.

  10. Balanced! Chemical Formula forPotassium Bromide • Write the two symbols for the ions in the compounds, placing the symbol for the cation first. +1 -1 K Br KBr • Determine the charge of each ion from the oxidation state on the periodic table. • If the charges are equal, drop them and write the formula.

  11. NOT Balanced! Calcium Bromide • If the charges are not equal, “lasso” the number only (not the sign) to write the formula. 1 + 2 2 - 1 Ca Br CaBr2 • After seeing more examples, complete practice problems 1-10 on your worksheet.

  12. Transition Elements and Roman Numerals • Some metals can form more than one type of ion and therefore, have more than one possible charge. • To tell which charge is used, the chemical name contains a Roman numeral. • The Roman numeral tells the charge of the cation.

  13. Transition Elements and Roman Numerals WARNING • Roman numerals are NEVER used in the chemical formula!!

  14. Rules to Write a Chemical Formula when Roman Numerals are Present • To write the chemical formula for Iron (III) Sulfide: • Write the two symbols for the ions in the compounds, placing the symbol for the cation first. • Get the charge of the metal from the Roman numeral in ( ) after the metal and look up the anion’s charge. - 2 2 Fe2S3 + 3 3 Fe S

  15. Oxygen has a charge of -2 and there are 3 for a total charge of -6. Mn can have a charge of +7, 6, 4, 2 or 3 Mn must have a charge of +6 to neutralize the -6 charge. Manganese (VI) Oxide Rules to Write a Chemical Name when Roman Numerals are Needed • If the metal has more than one oxidation state, the chemical name will contain a Roman numeral. • Now write the chemical name using a roman numeral to represent the charge of the Manganese. • Start with the anion to determine its overall negative charge. • You CANNOT lasso up to determine the Roman numeral. MnO3

  16. Fe can have a charge of +2 or 3 The 2 Fe ions must have an overall charge of +6. So 6/2 = +3. Oxygen has a charge of -2 and there are 3 for a total charge of -6. Iron (III) Oxide Let’s Try Again • Write the chemical name of Fe2O3. Rust Fe2O3 • Now write the chemical name. • Now do part C of your worksheet.

  17. Made of more than one element so it is a polyatomic ion. Polyatomic Ions in Names • The cation keeps its name. CaCO3 Carbonate Calcium • The polyatomic ion also keeps its name, even though it is an anion.

  18. Polyatomic Ions in FormulasBarium Phosphate • We recognize Phosphate as a polyatomic ion because it ends in “ate”. • Get the charge of the polyatomic ion from the chart. • Use the periodic table for the charge on your element.

  19. Ba3(PO4)2 Barium Phosphate • Let’s Lasso! • Write the chemical symbols. • Add each ion’s charge. • NO!! • Are the charges balanced? - 3 3 + 2 2 Ba PO4 • We have 2 “PO4” ions so we need parentheses to separate the ion from the extra subscript.

  20. Mg(OH)2 Let’s Try Again • Write the formula for Magnesium Hydroxide. + 2 2 - 1 1 Mg OH • We have 2 “OH” ions so we need parentheses to separate the ion from the subscript. • Now do part D of your worksheet.

  21. Covalent Compounds • Covalent compounds are made from 2 non-metals and are binary. • Since there are no ions involved, we don’t look at charges. • The subscript to the right of the element tells the prefix to use for that element. • SO2 = Sulfur Dioxide

  22. Mono = one Di = two Tri = three Tetra = four Penta = five Hexa = six Hepta = seven Octa = eight Nona = nine Deca = ten Triangle Hexagon Covalent Compound Prefixes

  23. TOXIC! LaughingGas Some Covalent Compounds NF3 nitrogen trifluoride N2Cl4 dinitrogen tetrachloride NO2 nitrogen dioxide dinitrogenmonoxide N2O • Now do part E of your worksheet.

  24. Naming Acids • Acids = compounds that give off hydrogen ions when dissolved in water. • Acids begin with H. • Acids will always have some H next to an anion. • The anion determines the name.

  25. Binary Acids • Binary Acids contain only 2 elements, the cation being hydrogen. Add the prefix hydro-, take the anion name and change the suffix -ide to –ic. • HCl(aq) Hydrochloric Acid • HF(aq) Hydrofluoric Acid • HI(aq) Hydroiodic Acid

  26. Binary Acids • Exceptions: • HCN = Hydrocyanic Acid CN = Cyanide • HN3 = Hydroazoic Acid azo = Nitrogen

  27. Oxyacids • Ternary Acids contain 3 elements, hydrogen, oxygen and one other element (a polyatomic ion). • The suffix is determined by the number of oxygens. • If the anion ends in -ate, change the suffix to –ic acid. HNO3 = Hydrogen & Nitrate = NitricAcid

  28. More Oxyacids H2SO4 = Hydrogen & Sulfate = SulfuricAcid HClO3 = Hydrogen & Chlorate = ChloricAcid

  29. More Oxyacids • If the anion has one less oxygen & ends in -ite, change the suffix to –ous acid. Hydrogen & Nitrite = HNO2 = NitrousAcid H2SO3 = Hydrogen & Sulfite = SulfurousAcid HClO2 = Hydrogen & Chlorite = ChlorousAcid

  30. HF H3P H3PO4 H3PO3 HCN H2CrO4 Hydrofluoric Acid Hydrophosphic Acid Phosphoric Acid Phosphorous Acid Hydrocyanic Acid Chromic Acid Name these Acids

  31. Oxyacids • If a third acid is formed with fewer oxygens than -ite, it is given the prefix hypo- and the suffix –ous. • E.g. HClO = Hydrogen & hypochlorite = HypochlorousAcid • If it has one more oxygen than -ate, it is given the prefix per- and the suffix –ic. • E.g. HClO4 = hydrogen & perchlorate = Perchloric Acid.

  32. Writing Formulas for Acids • Hydrogen will always be first. • The name tells you the anion. • Make sure the molecule is neutral. • If the name starts with the prefix hydro- and ends with -ic, there is no oxygen in the formula. • If there is no prefix, the suffix –ate comes from –ic and –itecomes from–ous.

  33. hydroiodic acid acetic acid carbonic acid phosphorous acid hydrobromic acid HI HC2H3O2 H2CO3 H3PO3 HBr Write Formulas for these Acids

  34. Naming Organic Compounds • Hydrocarbons are compounds made of only carbon and hydrogen linked in long chains. • Alkanes – have single bonded carbons so they are saturated.

  35. Naming Organic Compounds • Alkenes – have double bonded carbons so they are unsaturated. • Alkynes – have triple bonded carbons • We’ll work with alkanes so hydrocarbons will have the suffix –ane.

  36. Organic Stems

  37. Organic Compounds • If the atoms are linked in a ring rather than in a chain, the prefix cyclo- is added. • Hexane in a chain CH3-CH2- CH2- CH2- CH2- CH3. • Cyclohexane has 6 carbons in a ring. Each point represents a carbon.

  38. Organic Compounds • If the chain is straight: CnH2n+2 n=#carbons • E.g. C3H(2×3)+2 = C3H8 = Propane • CH3-CH2-CH3 • If the chain is cyclic: CnH2n • E.g. C3H6 = cyclopropane

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