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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.

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Presentation on theme: "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."— Presentation transcript:

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2 Chemical Names and Formulas Unit 5

3 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

4 Counting Atoms  If the subscripted number is outside of the parenthesis, it is distributed to all elements within the parenthesis.  Eg: Ca(NO 3 ) 2 = NO 3 x 2.  A preceeding coefficient is multiplied to all atoms in the compound.  Eg: 2NaCl = 2 sodium & 2 chlorine

5 Counting Atoms  Calcium Carbonate: CaCO 3. Ca = Calcium = 1 C =C =C =C = Carbon = 1 O =O =O =O = Oxygen = 3 Total atoms = 5

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

7 Counting Atoms  Acetic Acid: 2HC 2 H 3 O 2. H = H = H = H = Hydrogen = = 8 C = O =O =O =O = Oxygen = 4 Total atoms = 16 Carbon = 4  Now complete the Counting Atoms review worksheet.

8 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. IIIIMPORTANT: ALL COMPOUNDS ARE NEUTRAL!!! Cation+Anion= Ionic Compound

9 Chemical Formulas  Potassium Bromide = KBr  Calcium Bromide = CaBr 2  Lithium Fluoride = LiF  Lithium Oxide = Li 2 O  Note that the subscript has nothing to do with the name of the ionic compound.

10 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.

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

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

13 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.

14 Transition Elements and Roman Numerals  Roman numerals are NEVER used in the chemical formula!!

15 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. FeS Fe 2 S 3 2 3

16 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. MnO 3  Start with the anion to determine its overall negative charge. Mn can have a charge of +7, 6, 4, 2 or 3 Oxygen has a charge of -2 and there are 3 for a total charge of -6. Mn must have a charge of +6 to neutralize the -6 charge.  Now write the chemical name using a roman numeral to represent the charge of the Manganese. Manganese (VI) Oxide  You CANNOT lasso up to determine the Roman numeral.

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

18 Polyatomic Ions in Names  The cation keeps its name. CaCO 3 Calcium Carbonate Made of more than one element so it is a polyatomic ion.  The polyatomic ion also keeps its name, even though it is an anion.

19 Polyatomic Ions in Formulas Barium 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.

20 Barium Phosphate  Write the chemical symbols. BaPO 4  Add each ion’s charge  Are the charges balanced?  Let’s Lasso!  NO!! 2 3  We have 2 “PO 4 ” ions so we need parentheses to separate the ion from the extra subscript. Ba 3 (PO 4 ) 2

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

22 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.  SO 2 = Sulfur Dioxide

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

24 Some Covalent Compounds NF 3 nitrogen trifluoride N 2 Cl 4 dinitrogen tetrachloride NO 2 nitrogen dioxide N2ON2O dinitrogen monoxide TOXIC ! Laughing Gas  Now do part E of your worksheet.

25 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.

26 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

27 Binary Acids  Exceptions:  HCN = Hydrocyanic Acid CN = Cyanide  HN 3 = Hydroazoic Acid azo = Nitrogen

28 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. HNO 3 = Hydrogen & Nitrate = Nitric Acid

29 More Oxyacids H 2 SO 4 = Hydrogen & Sulfate = Sulfuric Acid HClO 3 = Hydrogen & Chlorate = Chloric Acid

30  If the anion has one less oxygen & ends in -ite, change the suffix to –ous acid. More Oxyacids HNO 2 = Hydrogen & Nitrite = Nitrous Acid H 2 SO 3 = Hydrogen & Sulfite = Sulfurous Acid HClO 2 = Hydrogen & Chlorite = Chlorous Acid

31 Name these Acids  HF H3PH3PH3PH3P  H 3 PO 4  H 3 PO 3  HCN  H 2 CrO 4  Hydrofluoric Acid  Hydrophosphic Acid  Phosphoric Acid  Phosphorous Acid  Hydrocyanic Acid  Chromic Acid

32 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 = Hypochlorous Acid  If it has one more oxygen than -ate, it is given the prefix per- and the suffix –ic.  E.g. HClO 4 = hydrogen & perchlorate = Perchloric Acid.

33 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 –ite comes from –ous.

34 Write Formulas for these Acids  hydroiodic acid  acetic acid  carbonic acid  phosphorous acid  hydrobromic acid  HI  HC 2 H 3 O 2  H 2 CO 3  H 3 PO 3  HBr

35 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.

36 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.

37 Organic Stems 1 carbon = meth- 6 carbons = hex- 2 carbons = eth- 7 carbons = hept- 3 carbons = prop- 8 carbons = oct- 4 carbons = but- 9 carbons = non- 5 carbons = pent- 10 carbons = dec-

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39 Organic Compounds  If the atoms are linked in a ring rather than in a chain, the prefix cyclo- is added.  Hexane in a chain CH 3 -CH 2 - CH 2 - CH 2 - CH 2 - CH 3.  Cyclohexane has 6 carbons in a ring. Each point represents a carbon.

40 Organic Compounds  If the chain is straight: C n H 2n+2 n=#carbons  E.g. C 3 H (2×3)+2 = C 3 H 8 = Propane  CH 3 -CH 2 -CH 3  If the chain is cyclic: C n H 2n  E.g. C 3 H 6 = cyclopropane


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