Introduction to Chemical Nomenclature

1. Introduction to Chemical Nomenclature Honors Chemistry Chang: Chapter 2

2. Noble Gas Halogen Alkali Earth Metal Period Alkali Metal Group Periodic Table of the Elements 2.4

3. H2 H2O NH3 CH4 A molecule is an aggregate of two or more atoms in a definite arrangement held together by chemical forces A diatomic molecule contains only two atoms H2, N2, O2, Br2, HCl, CO A polyatomic molecule contains more than two atoms O3, H2O, NH3, CH4 2.5

4. 2.6

5. molecular empirical H2O A molecular formula shows the exact number of atoms of each element in the smallest unit of a substance An empirical formula shows the simplest whole-number ratio of the atoms in a substance H2O CH2O C6H12O6 O3 O N2H4 NH2 2.6

6. 11 protons 11 electrons 11 protons 10 electrons Na+ Na 17 protons 18 electrons 17 protons 17 electrons Cl- Cl An ion is an atom, or group of atoms, that has a net positive or negative charge. cation – ion with a positive charge If a neutral atom loses one or more electrons it becomes a cation. anion – ion with a negative charge If a neutral atom gains one or more electrons it becomes an anion. 2.5

7. ionic compounds consist of a combination of cations and an anions • the formula is always the same as the empirical formula • the sum of the charges on the cation(s) and anion(s) in each formula unit must equal zero The ionic compound NaCl 2.6

8. A monatomic ion contains only one atom Na+, Cl-, Ca2+, O2-, Al3+, N3- A polyatomic ion contains more than one atom OH-, CN-, NH4+, NO3- 2.5

9. Chemistry Nomenclature

10. There are over 20 million chemical compounds known to scientists. Luckily, we don’t have to memorize all of them. We can follow the rules of chemical nomenclature to name them on sight (usually).

11. Two naming systems: Inorganic compounds:all non-organic compounds. Organic compounds: contain carbon, usually in combination with H, O, N and S. These account for >90% of chemical compounds.

12. A few carbon-containing compounds are considered to be inorganic compounds, and are named using inorganic nomenclature: CO, carbon monoxide CO2, carbon dioxide CS2, carbon disulfide carbon compounds containing CN−, CO32−, and HCO3−

13. Inorganic Compounds There are 4 categories of inorganic compounds: 1. ionic 2. molecular 3. acids and bases 4. hydrates

14. Binary Ionic Compounds Binary: compounds formed from two elements 1. The name of the element with a positive charge is first, followed by the element with the negative charge. 2. The metal always precedes the symbol for the nonmetal.

15. 3. The name of the metal is followed by the name of the nonmetal with the suffix –ide added. 4. Ionic compounds are made by combining anions and cations. The total positive charge must equal the total negative charge.

16. -ide derivatives of nonmetals F – fluoride N - nitride Cl – chloride P - phosphide Br – bromide As - arsenide I – iodide C - carbide O – oxide Se - selenide S – sulfide Te - telluride

17. 5. Certain metals, especially transition metals, can form more than one type of cation. To differentiate between each ionic form, use Roman numerals after the metal ion for clarification. This method of labeling metal cations is called the “Stock System” of nomenclature.

18. An older nomenclature system that is still in limited use assigns the -ous ending to the cation with a lower positive charge, and the -ic ending to the cation with a higher positive charge.

19. Fe2+ ferrous ion Fe3+ ferric ion FeCl2 ferrous chloride FeCl3 ferric chloride FeCl2 iron (II) chloride FeCl3 iron (III) chloride

20. Chemical Nomenclature • Binary Ionic Compounds barium chloride BaCl2 potassium oxide K2O magnesium sulfide MgS aluminum oxide Al2O3 2.7

21. Ionic Compounds Containing Polyatomic Ions 1. Some polyatomics end in –ide: OH-1 CN-1 2. Some polyatomics are cations: NH4+1 Hg2+2

22. SO32-: sulfite SO42-: sulfate What do you do if there are more than two forms of an anion containing the same elements?

23. 3. Most polyatomic anions contain multiple ions containing the same two elements (O and another element). The anion with the smaller number of oxygens uses the root of the element plus –ite. The anion with the higher number of oxygens uses the root plus –ate.

24. ClO-1 hypochlorite ClO2-1 chlorite ClO3-1 chlorate ClO4-1 perchlorate The prefix hypo- is used in the polyatomic with the fewest number of oxygen atoms; the prefix per- is used in the polyatomic with the highest number of oxygen atoms.

25. Parenthesis are used when more than one polyatomic anion is in a formula: CaCO3does not need parentheses Cr2(SO4)3There are 3 sulfate groups, so parentheses are needed.

26. Examples of Polyatomic Ionic Compounds Iron (III) nitrate Fe(NO3)3 Calcium sulfate CaSO4 Potassium dichromate K2Cr2O7 Chromium (II) permanganate Cr(MnO4)2 Sodium chlorate NaClO3 Sodium acetate NaC2H3O2 Tin (IV) phosphate Sn3(PO4)4

27. Binary Molecular Compounds 1. Usually composed of non-metallic or metalloid elements. 2. Nonmetal/nonmetal compounds don’t necessarily follow the balance charge rules. Two or more compounds may be formed between two nonmetals.

28. 3. The element further left in the periodic table is 1st in a molecule. NO CO2 4. The element closest to the bottom of a group is 1st in a molecule. SO2 BrCl3

29. Example: N and O N2O NO NO2 N2O4 N2O5 How do you differentiate between different compounds composed of the same elements?

30. To differentiate one compound from another, use Greek numerical prefixes: mono- hexa- di- hepta- tri- octa- tetra- nona- penta- deca-

31. 5. The prefix “mono-” is usually omitted from the first element. 6. If the addition of a prefix causes a/o or o/o to be next to each other, the first vowel is usually dropped.

32. Exceptions: • Compounds containing hydrogen: • Order can be first or second • May be named by systematic or • nonsystematic names (common names) • Name may or may not indicate • number of hydrogen atoms.

33. TOXIC! Laughing Gas Molecular Compounds HI hydrogen iodide NF3 nitrogen trifluoride SO2 sulfur dioxide N2Cl4 dinitrogen tetrachloride NO2 nitrogen dioxide N2O dinitrogen monoxide 2.7

34. Acids and Bases There are numerous definitions of acids and bases; the definition given here is that of an Arrhenius acid and base: Acid: yields H+ ions in water Base: yields OH- ions in water

35. Acids without oxygen 1. When the acid is pure, the hydrogen is named like a metal with a +1 charge, and the ending –ide is added to the anion. HCl is hydrogen chloride H2S is hydrogen sulfide

36. 2. When dissolved in water, refer to compounds by their acid names: • drop the word hydrogen • add the prefix hydro to the anion • root • change the –ide ending to –ic, • followed by the word acid

37. 2.7

38. Oxyacids 1. Name the polyatomic anion, and change –ite to –ous or change –ate to –ic. 2. Add the word “acid.”

40. sodium hydroxide NaOH potassium hydroxide KOH Ba(OH)2 barium hydroxide A base can be defined as a substance that yields hydroxide ions (OH-) when dissolved in water. 2.7

41. CuSO4 CuSO4•5H2O Hydrates are compounds that have a specific number of water molecules attached to them. barium chloride dihydrate BaCl2•2H2O lithium chloride monohydrate LiCl•H2O MgSO4•7H2O magnesium sulfate heptahydrate Sr(NO3)2•4H2O strontium nitrate tetrahydrate 2.7

42. 2.7

43. Organic chemistry is the branch of chemistry that deals with carbon compounds The simplest organic compounds are hydrocarbons, which contain only hydrogen and carbon.

44. The simplest class of hydrocarbons are straight chains of C and H, and are calledalkanes. CH4 methane C2H6 ethane C3H8 propane C4H10 butane C5H12 pentane C6H14 hexane C7H16 heptane C8H18 octane C9H20 nonane C10H22 decane

45. H H H O C C NH2 C C OH OH H H H H H H Functional Groups Determine how an organic compound will react methanol methylamine acetic acid 2.7