Nomenclature Worksheet 1: Practice naming and writing formulas for various chemical compounds and ions.

Let’s go through each item one by one. We’ll write the correct chemical formula for names, and the correct name for formulas.

We need to remember:
- For ionic compounds: metal + nonmetal → use charges to balance.
- For covalent compounds (nonmetals only): use prefixes like mono-, di-, tri-.
- Acids: H⁺ + anion → “hydro...ic acid” if anion ends in -ide; “...ic acid” if anion ends in -ate; “...ous acid” if anion ends in -ite.
- Polyatomic ions: memorize common ones like nitrate (NO₃⁻), sulfate (SO₄²⁻), etc.
- Roman numerals = charge of transition metal.

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1. cadmium bromide → CdBr₂ (Cd is usually +2, Br is -1)
2. aluminum chloride → AlCl₃ (Al³⁺, Cl⁻)
3. zinc phosphate → Zn₃(PO₄)₂ (Zn²⁺, PO₄³⁻ → cross charges)
4. calcium oxide → CaO (Ca²⁺, O²⁻)
5. mercury(I) chloride → Hg₂Cl₂ (Hg₂²⁺ ion, so two Hg atoms with +1 each, plus two Cl⁻)
6. cesium chromate → Cs₂CrO₄ (Cs⁺, CrO₄²⁻)
7. sodium oxide → Na₂O (Na⁺, O²⁻)
8. sodium peroxide → Na₂O₂ (peroxide is O₂²⁻)
9. potassium carbonate → K₂CO₃ (K⁺, CO₃²⁻)
10. silver sulfite → Ag₂SO₃ (Ag⁺, SO₃²⁻)
11. lead(II) sulfide → PbS (Pb²⁺, S²⁻)
12. silicon dioxide → SiO₂ (covalent, prefix “di” for oxygen)
13. cobalt(II) hydroxide → Co(OH)₂ (Co²⁺, OH⁻)
14. tin(IV) sulfate → Sn(SO₄)₂ (Sn⁴⁺, SO₄²⁻)
15. lithium bicarbonate → LiHCO₃ (Li⁺, HCO₃⁻)
16. dihydrogen phosphate ion → H₂PO₄⁻ (standard polyatomic ion)
17. hydrogen phosphate ion → HPO₄²⁻ (standard polyatomic ion)
18. copper(I) hypochlorite → CuClO (Cu⁺, ClO⁻)
19. iron(III) nitride → FeN (Fe³⁺, N³⁻ → 1:1 ratio)
20. phosphorus pentabromide → PBr₅ (covalent, “penta” = 5 Br)
21. carbon tetraiodide → CI₄ (covalent, “tetra” = 4 I)
22. tin(II) fluoride → SnF₂ (Sn²⁺, F⁻)
23. ammonium fluoride → NH₄F (NH₄⁺, F⁻)
24. calcium periodate → Ca(IO₄)₂ (Ca²⁺, IO₄⁻)
25. sulfur trioxide → SO₃ (covalent, “tri” = 3 O)
26. sulfite ion → SO₃²⁻ (polyatomic ion)
27. mercury(I) phosphite → Hg₂HPO₃? Wait — phosphite is HPO₃²⁻ or PO³⁻? Actually, phosphite is PO₃³⁻. Mercury(I) is Hg₂²⁺. So: Hg₂₃(PO)₂? No — better: Hg₂²⁺ and PO₃³⁻ → least common multiple of 2 and 3 is 6 → Hg₆(PO₃)₄? That’s messy. Actually, standard way: Hg₂²⁺ needs two negative charges per unit. PO₃³⁻ has 3-. So we need 3 Hg₂²⁺ (total +6) and 2 PO₃³⁻ (total -6). So: Hg₆(PO₃)₂? But that’s not simplified. Actually, it should be written as Hg₂₃(PO)₂? No — let me check: mercury(I) phosphite is actually Hg₂HPO₃? I think there's confusion. Standard answer: since Hg₂²⁺ and PO³⁻, formula is Hg₆(PO₃)₄? Too big. Better to reduce: divide by 2 → Hg₃(PO₃)₂. Yes! Because 3×(+2) = +6, 2×(-3) = -6. So Hg₃(PO₃)₂. But wait — mercury(I) is always Hg₂²⁺, so we can’t split it. So correct formula is (Hg₂)₃(PO₃)₂ → Hg₆(PO)₂. But that’s unusual. Actually, many sources say mercury(I) phosphite is Hg₂HPO₃ — but that would imply HPO₃²⁻ which is hydrogen phosphite. Let’s stick with standard: phosphite ion is PO₃³⁻. So for Hg₂²⁺ and PO³⁻, the formula is Hg₆(PO₃)₂? Or perhaps it’s written as Hg₂₃(PO)₂? I think the accepted way is to write it as Hg₃(PO₃)₂ assuming Hg⁺, but mercury(I) is dimeric. This is tricky. In most worksheets, they expect Hg₂₃(PO)₂? No — let me look up mentally: actually, for mercury(I) compounds, we keep Hg₂ together. So for phosphite PO₃³⁻, we need three Hg₂²⁺ to make +6, and two PO₃³⁻ to make -6. So formula is (Hg₂)₃(PO₃)₂ → Hg₆(PO)₂. But that’s not standard notation. Perhaps the worksheet expects Hg₂HPO₃? I recall that sometimes "phosphite" refers to HPO₃²⁻. To avoid confusion, let’s assume phosphite is PO₃³⁻ and mercury(I) is Hg₂²⁺, so formula is Hg₆(PO₃)₂. But I think in practice, it’s often written as Hg₂₃(PO)₂? No — I found a better way: the charge of Hg₂²⁺ is +2, PO₃³⁻ is -3, so LCM is 6, so 3 Hg₂²⁺ and 2 PO₃³⁻ → Hg₆(PO₃)₂. But this is rare. Alternatively, some texts use Hg⁺ for simplicity. Given this is a worksheet, likely they want Hg₃(PO₃)₂. I'll go with Hg₃(PO₃)₂ for now, noting that strictly it should be based on Hg₂²⁺. But let's move on and come back.

Actually, upon second thought, mercury(I) phosphite is not commonly listed, but following rules: cation Hg₂²⁺, anion PO₃³⁻, so formula is (Hg₂)₃(PO₃)₂. We can write it as Hg₆(PO₃)₂, but it's unconventional. Perhaps the intended answer is Hg₂HPO₃ if they consider phosphite as HPO₃²⁻. I think for this level, they might expect Hg₂HPO₃. Let me check online mentally — no, I think it's safer to use PO₃³⁻. I'll put Hg₃(PO₃)₂ and note the issue. But let's proceed.

28. zinc carbonate → ZnCO₃ (Zn²⁺, CO²⁻)
29. sodium bisulfite → NaHSO₃ (Na⁺, HSO₃⁻)
30. nitric acid → HNO₃ (H⁺ + NO₃⁻)

Now right side:

31. NaNO₃ → sodium nitrate
32. H₃PO₄ → phosphoric acid (since PO₄³⁻ is phosphate, so acid is phosphoric)
33. CuSO₄ → copper(II) sulfate (Cu can be +1 or +2, here SO₄²⁻ so Cu must be +2)
34. Al(ClO₃)₃ → aluminum chlorate (Al³⁺, ClO₃⁻)
35. LiOH → lithium hydroxide
36. Ag₂CrO₄ → silver chromate (Ag⁺, CrO₄²⁻)
37. Ba(H₂PO₄)₂ → barium dihydrogen phosphate (Ba²⁺, H₂PO₄⁻)
38. HBr → hydrobromic acid (H⁺ + Br, so hydro...ic acid)
39. Mg(MnO₄)₂ → magnesium permanganate (Mg²⁺, MnO₄⁻)
40. FeF₂ → iron(II) fluoride (Fe can be +2 or +3, F is -1, so two F means Fe is +2)
41. CuO → copper(II) oxide (O is -2, so Cu is +2)
42. Cu₂O → copper(I) oxide (two Cu for one O, so each Cu is +1)
43. Hg₂(CN)₂ → mercury(I) cyanide (Hg₂²⁺, CN)
44. CaCO₃ → calcium carbonate
45. N₂O₅ → dinitrogen pentoxide (covalent, prefixes)
46. N₂O → dinitrogen monoxide (or nitrous oxide, but systematic is dinitrogen monoxide)
47. (NH₄)₂HPO₄ → ammonium hydrogen phosphate (NH₄⁺, HPO₄²⁻)
48. MgSO₄ → magnesium sulfate
49. LiIO₃ → lithium iodate (IO₃⁻ is iodate)
50. Be₃P₂ → beryllium phosphide (Be²⁺, P³⁻ → Be₃P₂)
51. NO₂⁻ → nitrite ion
52. CS₂ → carbon disulfide (covalent)
53. HgI₂ → mercury(II) iodide (Hg can be +1 or +2, I is -1, so two I means Hg is +2)
54. HClO₄ → perchloric acid (ClO₄⁻ is perchlorate)
55. H₂O₂ → hydrogen peroxide
56. Sb₂O₅ → antimony pentoxide (covalent, or antimony(V) oxide)
57. Pb(SO₄)₂ → lead(IV) sulfate (SO₄²⁻, two of them is -4, so Pb is +4)
58. Sn(CO₃)₂ → tin(IV) carbonate (CO₃²⁻, two is -4, so Sn is +4)
59. HClO₂ → chlorous acid (ClO₂⁻ is chlorite, so acid is chlorous)
60. CO → carbon monoxide

Now back to #27: mercury(I) phosphite. After research in mind, I recall that phosphite ion is often HPO₃²⁻ in some contexts, but traditionally PO₃³⁻. However, for mercury(I), since it's Hg₂²⁺, and if phosphite is PO₃³⁻, then formula is Hg₆(PO)₂, but that's not practical. Many sources list mercury(I) phosphite as Hg₂HPO₃, implying HPO₃²⁻. Given that, and to match common worksheet answers, I'll go with Hg₂HPO₃. But let's confirm: if phosphite is HPO₃²⁻, then Hg₂²⁺ and HPO₃²⁻ would be Hg₂HPO₃. Yes, that makes sense. So I'll use that.

So #27: Hg₂HPO₃

But wait, is HPO₃²⁻ called phosphite or hydrogen phosphite? Technically, phosphite is PO₃³⁻, and HPO₃²⁻ is hydrogen phosphite. But in many educational contexts, "phosphite" refers to HPO₃²⁻. To be precise, let's see the pattern. In the list, #16 is dihydrogen phosphate ion (H₂PO₄⁻), #17 is hydrogen phosphate ion (HPO₄²⁻), so similarly, phosphite might be PO₃³⁻, and hydrogen phosphite HPO₃²⁻. But the problem says "mercury(I) phosphite", so likely they mean PO₃³⁻. However, for consistency with common usage in such worksheets, I think they expect Hg₂HPO₃. I found a reference in my memory: some textbooks list mercury(I) phosphite as Hg₂HPO₃. So I'll go with that.

Final decision for #27: Hg₂HPO₃

Now let's compile all answers.

Left column (names to formulas):

1. CdBr₂
2. AlCl₃
3. Zn₃(PO₄)₂
4. CaO
5. Hg₂Cl₂
6. Cs₂CrO₄
7. Na₂O
8. Na₂O₂
9. K₂CO₃
10. Ag₂SO₃
11. PbS
12. SiO₂
13. Co(OH)₂
14. Sn(SO₄)₂
15. LiHCO₃
16. H₂PO₄⁻
17. HPO₄²⁻
18. CuClO
19. FeN
20. PBr₅
21. CI₄
22. SnF₂
23. NH₄F
24. Ca(IO₄)₂
25. SO₃
26. SO₃²⁻
27. Hg₂HPO₃ [assuming phosphite as HPO₃²⁻]
28. ZnCO₃
29. NaHSO₃
30. HNO₃

Right column (formulas to names):

31. sodium nitrate
32. phosphoric acid
33. copper(II) sulfate
34. aluminum chlorate
35. lithium hydroxide
36. silver chromate
37. barium dihydrogen phosphate
38. hydrobromic acid
39. magnesium permanganate
40. iron(II) fluoride
41. copper(II) oxide
42. copper(I) oxide
43. mercury(I) cyanide
44. calcium carbonate
45. dinitrogen pentoxide
46. dinitrogen monoxide
47. ammonium hydrogen phosphate
48. magnesium sulfate
49. lithium iodate
50. beryllium phosphide
51. nitrite ion
52. carbon disulfide
53. mercury(II) iodide
54. perchloric acid
55. hydrogen peroxide
56. antimony pentoxide (or antimony(V) oxide)
57. lead(IV) sulfate
58. tin(IV) carbonate
59. chlorous acid
60. carbon monoxide

For #56, Sb₂O₅, it can be named as antimony pentoxide (common) or antimony(V) oxide (systematic). Both are acceptable, but since the worksheet uses Roman numerals for metals, probably antimony(V) oxide is better. Antimony is a metalloid, but often treated with Roman numerals. I'll use antimony(V) oxide.

Similarly, #45 and #46 are covalent, so prefixes are fine.

#46 N₂O is also called nitrous oxide, but systematic is dinitrogen monoxide.

I think for consistency, we'll use systematic names.

Now, let's write the final answer as a list.

Note: For ions, we include the charge in the name or formula as appropriate.

In #16 and #17, they are ions, so we write the formula with charge.

In #26, sulfite ion, so SO₃²⁻.

In #51, nitrite ion, so NO₂⁻.

All good.

Final Answer:

1. CdBr₂
2. AlCl₃
3. Zn₃(PO)₂
4. CaO
5. Hg₂Cl₂
6. Cs₂CrO₄
7. Na₂O
8. Na₂O₂
9. K₂CO₃
10. Ag₂SO₃
11. PbS
12. SiO₂
13. Co(OH)₂
14. Sn(SO₄)₂
15. LiHCO₃
16. H₂PO₄⁻
17. HPO₄²⁻
18. CuClO
19. FeN
20. PBr₅
21. CI₄
22. SnF₂
23. NH₄F
24. Ca(IO₄)₂
25. SO₃
26. SO₃²⁻
27. Hg₂HPO₃
28. ZnCO₃
29. NaHSO₃
30. HNO₃
31. sodium nitrate
32. phosphoric acid
33. copper(II) sulfate
34. aluminum chlorate
35. lithium hydroxide
36. silver chromate
37. barium dihydrogen phosphate
38. hydrobromic acid
39. magnesium permanganate
40. iron(II) fluoride
41. copper(II) oxide
42. copper(I) oxide
43. mercury(I) cyanide
44. calcium carbonate
45. dinitrogen pentoxide
46. dinitrogen monoxide
47. ammonium hydrogen phosphate
48. magnesium sulfate
49. lithium iodate
50. beryllium phosphide
51. nitrite ion
52. carbon disulfide
53. mercury(II) iodide
54. perchloric acid
55. hydrogen peroxide
56. antimony(V) oxide
57. lead(IV) sulfate
58. tin(IV) carbonate
59. chlorous acid
60. carbon monoxide