Chapter 9 chemical names and formulas

1. Chapter 9 chemical names and formulas Calcium Carbonate Potassium Sulfate Hydrogen Phosphate Carbon Dioxide Strontium Sulfate Dinitrogen Monoxide

2. Naming Ions Monatomic Ions Single atom with a positive or negative charge i. Cation 1. Lose electrons 2. Positive charge 3. Name remains the same Na is Sodium Na+ is Sodium cation

3. ii. Anion 1. Gain electrons 2. Negative charge 3. Name starts with the stem and ends in -ide N is Nitrogen N3- is Nitride

4. iii. Transition Metals 1. Lose electrons - cations 2. Positive charge 3. Transition metals may lose a different number of electrons creating ions with a different charge 4. Two ways to name them

5. a. Stock system -most common way of naming i. A roman numeral is placed next (with no spaces) to the name of the element indicating the charge Fe2+ is Iron(II) ion Fe3+ is Iron(III) ion Co2+ is Cobalt(II) ion Co3+ is Cobalt(III) ion

6. b. Classic system -older, less useful way i. Root word with –ous at the end of the ion with the smaller charge and –ic at the end of the ion with the larger charge Fe2+ is Ferrous ion Fe3+ is Ferric ion Co2+ is Cobaltous ion Co3+ is Cobaltic ion

7. **There are special metals that change their charge – Tin (Sn) and Lead (Pb) FYI – many of these transition metal cations are colored and are used as pigments which are used to make different colored paints

8. Polyatomic Ions Ions composed of more than one atom i. Most that end in -ite or -ate contain Oxygen ii. If the formula begins with H then the name usually begins with Hydrogen iii. The names need to be memorized

9. Naming Ionic Compounds Compound Names i. Names of compounds used to be determined by the person who discovered it and the name related to the compounds property or what it was used for NaHCO3baking soda – used to bake cakes CaSO4 + ½H2Oplaster of Paris – used to make plaster faces

10. ii. As more compounds were discovered, it became harder to memorize all the unrelated names. iii. Antione Lavoisier worked with other chemists to devise a naming system Make it easier to identify names

11. Binary Ionic Compounds i. Binary Compounds Ionic or molecular compounds composed of two elements ii. Binary Ionic Compounds Ionic compound composed of a cation and an anion

12. Naming Binary Ionic Compounds i. Name the cation first ii. Name the anion second Examples: Cation Anion Ionic Compound Cs2O Cesium Oxide Cesium Oxide NaCl Sodium Chloride Sodium Chloride SrF2 Strontium Fluoride Strontium Fluoride SnF2 Remember Tin is a special metal and needs roman numerals * * SnS2

13. Cation Anion Ionic Compound SnF2 Tin(II) Fluoride Tin(II) Fluoride SnS2 Sulfide Tin(IV) Sulfide Tin(IV)

14. Writing Formulas for Binary Ionic Compounds i. If you know the name of the Ionic Compound you can write the formula ii. Write the symbol of the cation and charge iii. Write the symbol of the anion and charge iv. Add the required subscripts (the positive and negative charges must balance

15. Examples: Cation Anion Ionic Compound Potassium Chloride K+ Cl- KCl Calcium Bromide CaBr2 Ca2+ Br- Iron(III) Oxide Fe2O3 Fe3+ O2-

16. Naming compounds with polyatomic ions i. Name the cations ii. Name the polyatomic anion Examples: Compound Cation Polyatomic ion Calcium Carbonate CaCO3 Calcium Carbonate Potassium Hydrogen Phosphate Hydrogen Phosphate K2HPO4 Potassium K2SO4 Potassium Sulfate Potassium Sulfate

17. Writing formulas for compounds with polyatomic ions i. If you know the name of a compound you can write the formula ii. Write the symbol of the cation and the charge iii. Write the symbol of the polyatomic anion and the charge iv. Add the required subscripts (positive and negative charges must balance)

18. Examples: Compound Cation Polyatomic ion Calcium Nitrate Ca2+ NO3- Ca(NO3)2 Strontium Sulfate SrSO4 Sr2+ SO42-

19. Naming Molecular Compounds Binary Molecular compounds Two elements covalently bonded Naming Binary Molecular compounds i. A prefix is added to an element to state how many of each atom is present (prefix is always added to the second element and only added to the first if the number is greater than one)

20. ii. -ide is added to the end of the second molecule Examples: CO Carbon Monoxide Carbon Dioxide CO2 Dinitrogen Monoxide N2O Cl2O8 Dichlorine Octoxide

21. Writing formulas for Molecular Compounds i. Write the symbol for the first nonmetal ii. Write the symbol for the second nonmetal iii. Use the prefixes to tell you the subscripts

22. Examples: First Second Formula Silicon Monocarbide Si C SiC Dinitrogen tetroxide N2O4 N2 O4 Phosphorus pentachloride P Cl5 PCl5 Chlorine trifluoride Cl F3 ClF3

23. Acids Acids - Group of ionic compounds that contains one or more hydrogen atoms and produces hydrogen ions (H+) when dissolved in water. Naming Acids Three Rules 1. When anion ends in –ide the acid name begins with the prefix hydro-, the stem of the anion with the suffix –ic followed by acid

24. Example: HCl * Anion is Chloride * Name begins with hydro * Then the stem of the anion -chlor * Then the suffix -ic * Followed by Acid acid hydro chlor ic

25. 2. When anion ends in –ite, the acid name is the stem of the anion with the suffix –ous followed by the word acid Example: H2SO3 * Anion is Sulfite (pg 257) * Name begins with stem of anion Sulfur * Then the suffix -ous * Followed by Acid sulfur ous acid

26. 3. When anion ends in –ate, the acid name is the stem of the anion with the suffix –ic followed by the word acid Example: HNO3 * Anion is Nitrate (pg 257) * Name begins with stem of anion Nitr * Then the suffix -ic * Followed by Acid nitr ic acid

27. Writing formulas for Acids i. The general formula for acids is HnX where X is the monatomic or polyatomic anion and n is a subscript for the number of hydrogen atoms needed to make the compound neutral ii. Use the three rules for naming acids in reverse and then balance

28. Example: Hydrobromic acid * Followed by Acid --- Formula is HnX * Hydro and -ic --- anion ends in -ide * Balance H+ Br- HBr

29. Phosphorous acid * Followed by Acid --- Formula is HnX * -ous --- anion ends in –ite (pg 257) * Balance H+ PO33- H3PO3

30. Sulfuric acid * Followed by Acid --- Formula is HnX * -ic --- anion ends in –ate (pg 257) * Balance H+ SO42- H2SO4

31. Names and formulas for Bases bases - Ionic compound that produces hydroxide ion (OH-) when dissolved in water Naming i. Name the cation ii. Name the anion (hydroxide)

32. Examples: NaOH * Name the cation - Sodium * Name the anion - Hydroxide Sodium Hydroxide Al(OH)3 Aluminum Hydroxide

33. Writing formulas for bases i. Write the symbol for the cation and charge ii. Write the symbol for the anion and charge (OH-) iii. Balance the formula (positive and negative charges must balance)

34. Examples: Potassium hydroxide * Cation and charge – K+ * Anion and charge – OH- * Balance K+ OH- KOH

35. Laws governing Formulas and Names Naming using these methods is possible because elements form compounds in predictable ways

36. Laws of Definite Proportions In samples of any chemical compound, the masses of the elements are always in the same proportions because atoms combine in simple whole number ratios Laws of Multiple Proportions Whenever the same two elements form more than one compound, the different masses of one element that combine with the same masses of the other elements are in the ratio of small whole numbers