Understanding Chemical Nomenclature and Writing Formulas

1. Chapter 2 Part 2 Nomenclature (Naming Compounds) Writing Formulas

2. Systematic Naming • There are too many compounds to remember the names of them all. • Compound is made of two or more elements. • Name should tell us how many and what type of atoms. • Rules were established

3. Representative elements 1 20 15 2 17 13 14 • The Main Group elements 16

4. Transition metals • The transition, or groups 3-12 elements

5. Types of Particles • There are three types of particles all matter is made off: • IONS (ionic compounds, metals) • ATOMS (Noble gases) • MOLECULES (molecular compounds)

6. Atoms and Ions • Atoms are electrically neutral. • Same number of protons and electrons. • Ions are atoms, or groups of atoms, with a charge. • Different numbers of protons and electrons. • Only electrons can move. • Negative ions formed by gaining electron • Positive ions formed by losing electrons.

7. Anion • A negative ion. • Has gained electrons. • Only non metals can gain electrons. • Charge is written as a superscript on the right. F-1 Has gained one electron O-2 Has gained two electrons

8. Cations • Positive ions. • Formed by losing electrons. • More protons than electrons. • Metals form cations. K+1 Has lost one electron Ca+2 Has lost two electrons

9. Types of Chemical Bonds • IONIC: • positive and negative ions attract each other. (Electrostatic attraction) • COVALENT: • two atoms share one or more (up to three) pairs of electrons • METALLIC: • positive ions are surrounded by freely moving electrons (metals)

10. Compounds • Follow the Law of Definite Proportion. • Have a constant composition. • Two types: ionic and molecular.

11. Two Types of Compounds • Molecular compounds • Made of molecules. • Made by joining nonmetal atoms together into molecules.

12. Two Types of Compounds • Ionic Compounds • Made of cations and anions. • Metals and nonmetals or polyatomic ions. • The electrons lost by the cation are gained by the anion. • The cation and anions surround each other. • Smallest piece is a FORMULA UNIT.

13. Two Types of Compounds Ionic Molecular Smallest piece Formula Unit Molecule Types of elements Metal and Nonmetal, polyatomic ions Nonmetals Solid, liquid or gas State solid Melting Point Low <300ºC, depends on molecular mass High >300ºC

14. Chemical Formulas • Shows the kind (identity) and number of atoms in the smallest piece of a substance. Shorthand notation. • Molecular formula- number and kinds of atoms in a molecule. Indicated by a SUBSCRIPT • CO2 • C6H12O6

15. Types of Formulas (1) • Molecular formula: • indicates the composition of a molecular compound. • Formula unit: • depicts the composition of an ionic compound. Shows the ratio between the ions in the formula.

16. Types of Formulas (2) • Structural formula: • depicts the structure of a molecule, or an ion. Shows the bonding pattern within the unit. • Condensed structural formulas: • hybrid between molecular and structural formulas. Highlights the presence of reactive or special groups.

17. Types of Formulas (3) EMPIRICAL FORMULA: • indicates the simplest whole-number ratios in which atoms of the elements are present in the compound Ionic compounds : usually represented by empirical formula (NaCl). Exception: Hg2Cl2

18. Molecular Compounds Writing names and Formulas

19. Molecular Compounds hemoglobin water

20. Molecules • Small group of atoms held together by covalent bonds. Made up from non-metallic elements only!!!! • Neutral particles. • #protons = # electrons • Examples: CH4, NO2, CO, CO2, C6H12O6, C2H6

21. Nomenclature ofMolecules • Molecular compounds name tells you the number of atoms. • Uses prefixes to tell the number of atoms

22. Prefixes • 1 mono- • 2 di- • 3 tri- • 4 tetra- • 5 penta- • 6 hexa- • 7 hepta- • 8 octa-

23. Prefixes • 9 nona- • 10 deca- • To write the name write two words

24. Prefixes • 9 nona- • 10 deca- • To write the name write two words 1- Prefix name 2- Prefix name + -ide

25. Prefixes • 9 nona- • 10 deca- • To write the name write two words • One exception is we don’t write mono- if there is only one of the first element. Prefix name Prefix name -ide

26. Prefixes • 9 nona- • 10 deca- • To write the name write two words • One exception is we don’t write mono- if there is only one of the first element. • No double vowels when writing names (oa oo) Prefix name Prefix name -ide

27. Write formulas for these • diphosphorus trioxide • tetraiodide nonoxide • sulfur hexachloride • dinitrogen trioxide • carbon tetrachloride • diphosphorus trisulfide • magnesium nitride

28. Ionic Compounds • Represented by formula unit • The smallest whole number ratio of atoms in an ionic compound. • Ions surround each other so you can’t say which is hooked to which.

29. Ionic compounds

30. Ionic Compounds

31. Charges on Ions • For most of the Representative Elements (Groups 1, 2, 13-17 elements), the Periodic Table can tell what kind of ion they will form from their location. • Elements in the same group have similar properties. • Including the charge when they are ions.

32. Group 14: does not form ions +1 +2 +3 -3 -2 -1

33. What about the others? • We have to figure those out some other way. • Check the periodic table • Examples:

34. Naming ions • We will use the systematic way. • Cation- if the charge is always the same (Group 1) just write the name of the metal. • Transition metals can have more than one type of charge. • Indicate the charge with Roman numerals in parenthesis.

35. Name these • Na+1 • Ca+2 • Al+3 • Fe+3 • Fe+2 • Pb+2 • Li+1

36. Write Formulas for these • Potassium ion • Magnesium ion • Copper (II) ion • Chromium (VI) ion • Barium ion • Mercury (II) ion

37. Naming Anions • Anions are always the same. • Change the element ending to – ide • F-1 Fluorine change to fluoride

38. Name these • Cl-1 • N-3 • Br-1 • O-2 • Ga+3

39. Write these • Sulfide ion • iodide ion • phosphide ion • Strontium ion

40. Polyatomic ions • Groups of atoms that stay together and have a charge. • You must memorize these. • Acetate C2H3O2-1 • Nitrate NO3-1 • Nitrite NO2-1 • Hydroxide OH-1 • Permanganate MnO4-1 • Cyanide CN-1

41. Sulfate SO4-2 Sulfite SO3-2 Carbonate CO3-2 Chromate CrO4-2 Dichromate Cr2O7-2 Phosphate PO4-3 Phosphite PO3-3 Ammonium NH4+1 Polyatomic ions

42. Ions in Ionic Compounds

43. Naming Binary Ionic Compounds • Binary Compounds - 2 elements. • Ionic - a cation and an anion. • To write the names just name the two ions. • Easy with Representative elements. • Group 1 • NaCl = Na+ Cl- = sodium chloride • MgBr2 = Mg+2 Br- = magnesium bromide

44. Naming Binary Ionic Compounds • The problem comes with the transition metals. • Need to figure out their charges. • The compound must be neutral. • same number of + and – charges. • Use the anion to determine the charge on the positive ion.

45. Naming Binary Ionic Compounds • Write the name of CuO • Need the charge of Cu • O is -2 • copper must be +2 • Copper (II) chloride • Name CoCl3 • Cl is -1 and there are three of them = -3 • Co must be +3 Cobalt (III) chloride

46. Naming Binary Ionic Compounds • Write the name of Cu2S. • Since S is -2, the Cu2 must be +2, so each one is +1. • copper (I) sulfide • Fe2O3 • Each O is -2 3 x -2 = -6 • 3 Fe must = +6, so each is +2. • iron (III) oxide

47. Naming Binary Ionic Compounds • Write the names of the following • KCl • Na3N • CrN • Sc3P2 • PbO • PbO2 • Na2Se

48. Ternary Ionic Compounds • Will have polyatomic ions • At least three elements • name the ions • NaNO3 • CaSO4 • CuSO3 • (NH4)2O

49. Ternary Ionic Compounds • LiCN • Fe(OH)3 • (NH4)2CO3 • NiPO4

50. Writing Formulas • The charges have to add up to zero. • Get charges on pieces. • Cations from name of table. • Anions from table or polyatomic. • Balance the charges by adding subscripts. • Put polyatomics in parenthesis.