Naming Compounds and Writing Formulas

1. Naming Compounds and Writing Formulas

2. Periodic Table • Recall that the periodic table is more than a list of elements. • Elements are put in columns because of similar properties. • Each column is called a group.

3. Representative Elements 0 1A 4A 6A • The group A elements 2A 3A 5A 7A

4. Metals

5. Transition Metals • The Group B elements

6. Nonmetals

7. Metalloids

8. Systematic Naming • There are too many compounds to remember the names of them all. • A compound is made of two or more elements. • The name should tell us how many and what type of atoms.

9. Types of Compounds • There are two types of compounds: ionic compounds and molecular compounds.

10. Ionic Compounds • The simplest ratio of the ions represented in an ionic compound is called a formula unit. • The overall charge of any formula unit is zero. • In order to write a correct formula unit, one must know the charge of each ion.

11. Atoms and Ions • Atoms are electrically neutral. • They have the same number of protons and electrons. • Ions are atoms, or groups of atoms, with a charge. • Ions have a different numbers of electrons.

12. Anions • An anion is a negative ion. • An anion has gained electrons. • Nonmetals can gain electrons. • The charge is written as a superscript on the right. F-1 Has gained one electron O-2 Has gained two electrons

13. Cations • A cation is a positive ion. • It is formed by losing electrons. • There are more protons than electrons. • Metals form cations. K1+ Has lost one electron Ca2+ Has lost two electrons

14. Ionic Compounds • The charges of monatomic ions, or ions containing only one atom, can often be determined by referring to the periodic table or table of common ions based on group number. • The charge of a monatomic ion is equal to its oxidation number.

15. Charges on Ions • For most of the Group A 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.

16. Charges on Ions:Oxidation Numbers 1+ 2+ 3+ 3- 2- 1-

17. Naming Cations • We will use the systematic way. • For cations, if the charge is always the same (Group A) just write the name of the metal.

18. Naming Cations • Transition metals (as well as tin and lead) can have more than one type of charge. • Indicate the charge with Roman numerals in parenthesis. • Zinc (Zn2+) and silver (Ag1+), although transition metals, only have one possible charge. Roman numerals ARE NOT used for zinc and silver.

19. Example • Li1+ • Li is the symbol for lithium. • Lithium is a Group 1A metal, so the charge is always the same. Write the name of the metal. • Li1+ is called the Lithium ion.

20. Example • Sr2+ • Sr is the symbol for strontium. • Strontium is a Group 2A metal, so the charge is always the same. Write the name of the metal. • Sr2+ is called the Strontium ion.

21. Example • Fe2+ • Fe is the symbol for iron. • Iron is a transition metal, so the charge is not always the same. Write the name of the metal, indicating the charge with Roman numerals in parenthesis. • Fe2+ is called the Iron (II) ion.

22. Example • Pb2+ • Pb is the symbol for lead. • Lead is a Group 4A metal, and the charge is not always the same. Write the name of the metal, indicating the charge with Roman numerals in parenthesis. • Pb2+ is called the Lead (II) ion.

23. Problem • Name the following cations. • Ca2+ Calcium ion Aluminum ion • Al3+ Tin (IV) ion • Sn4+

24. Problem • Name the following ions. • Na1+ Sodium ion Iron (III) ion • Fe3+ Copper (I) ion • Cu1+

25. Writing the Formulas for Cations • Write the formula for the metal. • If a Roman numeral is in parenthesis use that number for the charge. Indicate the charge with a superscript.

26. Writing the Formulas for Cations • If no Roman numeral is given, find the Group A metal on the periodic table and determine the charge from the column number.

27. Example • Nickel (II) ion • Ni is the symbol for nickel. • Nickel is a transition metal, which is the reason why the charge with Roman numerals in parenthesis was included. • The formula for the nickel (II) ion is Ni2+.

28. Example • Gallium ion • Ga is the symbol for gallium. • Gallium is a Group 3A metal and its charge is always the same (+3). • The formula for the gallium ion is Ga3+.

29. Problem • Write the formulas for the following cations. Mg2+ • Magnesium ion Cu2+ • Copper (II) ion • Potassium ion K1+

30. Problem • Write the formulas for the following ions. • Silver ion Ag1+ • Chromium (VI) ion Cr6+ • Mercury (II) ion Hg2+

31. Naming Anions • Naming monatomic anions is always the same. • Change the element ending to – ide • Example: F1- • F is the symbol for fluorine, F1- is fluor ide. ine.

32. Example • Cl1- • Cl is the symbol for chlorine. • Chlorine is a Group 7A nonmetal, so the charge is always the same (-1). • Cl1- is called the chloride ion.

33. Example • O2- • O is the symbol for oxygen. • Oxygen is a Group 6A nonmetal, so the charge is always the same (-2). • O2- is called the oxide ion.

34. Problem • Name the following anions. • S2- sulfide ion • Br1- bromide ion • N3- nitride ion

35. Problem • Name the following anions. • As3- arsenide ion • Te2- telluride ion

36. Writing the Formulas for Anions • Write the formula for the nonmetal. • Find the Group A nonmetal on the periodic table and determine the charge from the column number.

37. Problem • Write the formulas for the following anions. • iodide ion I1- • phosphide ion P3-

38. Problem • Write the formulas for the following anions. • selenide ion Se2- • carbide ion C4-

39. Ionic Compounds • Oxidation numbers can be used to determine the chemical formulas for ionic compounds. • If the oxidation number of each ion is multiplied by the number of that ion present in a formula unit, and then the results are added, the sum must be zero.

40. Ionic Compounds • In the formula for an ionic compound, the symbol of the cation is written before that of the anion. • Subscripts, or small numbers written to the lower right of the chemical symbols, show the numbers of ions of each type present in a formula unit.

41. Binary Ionic Compounds • Binaryionic compounds are composed of a metal bonded with a nonmetal. • Name the metal ion using a Roman numeral in parenthesis if necessary. • Follow this name with the name of the nonmetal ion.

42. Example • Name the following binary ionic compounds. • NaCl Sodium chloride • Ca3P2 Calcium phosphide

43. Example • Name the following binary ionic compounds. • CuO Copper (II) oxide • SnBr2 Tin (II) bromide

44. Problem • Name the following binary ionic compounds. • Fe2S3 Iron (III) sulfide • AlF3 Aluminum fluoride

45. Problem • Name the following binary ionic compounds. • KCl Potassium chloride • Na3N Sodium nitride

46. Problem • Name the following binary ionic compounds. • CrN Chromium (III) nitride • PbO2 Lead (IV) oxide

47. Writing Formulas for Binary Ionic Compounds • Write the symbol for the metal. Determine the oxidation number from either the column number or the Roman numeral and write it as a superscript to the right of the metal’s symbol.

48. Writing Formulas for Binary Ionic Compounds • To the right of the metal’s symbol, write the symbol for the nonmetal. Determine the oxidation number from the column number and write it as a superscript to the right of the nonmetal’s symbol.

49. Writing Formulas for Binary Ionic Compounds • Example: potassium fluoride 1+ 1- K F

50. Writing Formulas for Binary Ionic Compounds • If the two oxidation numbers add together to get zero, the formula is a one-to-one ratio of the elements.