chem nomenclature and oxidation states

7. Rule: How to name ionic compounds

Name the metal (cation) first, then the nonmetal (anion) with “-ide.”

8. Explain: Why Roman numerals are used in ionic names

They show the metal’s charge when multiple oxidation states are possible.

9. Example: Write both names — FeCl₂ and FeCl₃

Iron(II) chloride; Iron(III) chloride.

10. Define: Polyatomic ion

A charged group of covalently bonded atoms acting as one ion.

11. Explain: Why parentheses appear in formulas like Ca(NO₃)₂

The polyatomic ion appears more than once.

12. Define: Subscript numbers in a formula

Show how many of each atom or ion are present.

13. Define: Oxidation state (oxidation number)

The apparent charge of an atom after losing or gaining electrons.

14. Rule: Sum of oxidation states in a neutral compound

Equals 0.

15. Rule: Sum of oxidation states in a polyatomic ion

Equals the ion’s total charge.

16. State: Oxidation states of Group 1 metals

+1.

17. State: Oxidation states of Group 2 metals

+2.

18. State: Oxidation states of Group 3 metals

+3.

19. State: Oxidation state of Fluorine

−1.

20. State: Oxidation state of Oxygen

−2.

21. State: Oxidation state of Hydrogen

+1.

22. Define: Free element rule

Any uncombined element has oxidation number 0.

23. Find oxidation state: Nitrogen in NO₃⁻

+5.

24. Find oxidation state: Sulfur in H₂SO₄

+6.

25. Find oxidation state: Iron in Fe₂O₃

+3.

26. Define: Ionic compound charge rule

Total positive charge equals total negative charge.

27. Define: Oxidation state purpose

Determines how elements combine and formula subscripts.

28. Explain: “Swap and drop” method

Swap ion charges as subscripts, drop signs, simplify.

29. Write formula: Calcium nitrate

Ca(NO₃)₂.

30. Write formula: Aluminum oxide

Al₂O₃.

31. Write formula: Ammonium sulfate

(NH₄)₂SO₄.

32. Write name: Na₂S

Sodium sulfide.

33. Write name: AlN

Aluminum nitride.

34. Write name: Li₂O

Lithium oxide.

35. Write name: MgCl₂

Magnesium chloride.

36. Write name: CaF₂

Calcium fluoride.

37. Define: Binary acid

Acid of hydrogen + nonmetal; hydro- + root + -ic acid.

38. Define: Oxyacid

Acid of hydrogen + polyatomic ion; -ate → -ic, -ite → -ous.

39. Write name: H₂SO₄

Sulfuric acid.

40. Write name: HNO₂

Nitrous acid.

41. Define: Common mistake — forgetting Roman numerals

Transition metals need numerals for multiple charges.

42. Define: Common mistake — “mono-” rule

Never use “mono-” for the first element in covalent names.

43. List: Prefixes for covalent compounds

mono-, di-, tri-, tetra-, penta-, hexa-, hepta-, octa-, nona-, deca-.

44. Write name: CO₂

Carbon dioxide.

45. Write name: P₂O₅

Diphosphorus pentoxide.

46. Write formula: Nitrogen trichloride

NCl₃.

47. Write formula: Sulfur hexafluoride

SF₆.

48. Define: Nitride ion

N³⁻.

49. Define: Oxide ion

O²⁻.

50. Define: Sulfide ion

S²⁻.

51. Define: Phosphide ion

P³⁻.

52. Define: Fluoride ion

F⁻.

53. Define: Chloride ion

Cl⁻.

54. Define: Bromide ion

Br⁻.

55. Define: Iodide ion

I⁻.

56. Define: Hydroxide ion

OH⁻.

57. Define: Nitrate ion

NO₃⁻.

58. Define: Nitrite ion

NO₂⁻.

59. Define: Sulfate ion

SO₄²⁻.

60. Define: Sulfite ion

SO₃²⁻.

61. Define: Phosphate ion

PO₄³⁻.

62. Define: Carbonate ion

CO₃²⁻.

63. Define: Acetate ion

C₂H₃O₂⁻.

64. Define: Bicarbonate (hydrogen carbonate) ion

HCO₃⁻.

65. Define: Ammonium ion

NH₄⁺.