Naming Rules Worksheet #1 for covalent compounds, featuring instructions and a list of chemical formulas to name.

Let’s go through each compound one by one and name them correctly using the rules for covalent compounds (nonmetals only) and acids (if it starts with H and is on the Acids List).

We’ll use these key ideas:
- For covalent compounds (two nonmetals):
→ First element: keep its name, add prefix if more than 1 atom.
→ Second element: change ending to “-ide”, add prefix always (even if 1).
→ Prefixes: mono=1, di=2, tri=3, tetra=4, penta=5, hexa=6, hepta=7, octa=8, nona=9, deca=10.
→ Exception: don’t use “mono” on first element.

- For acids (start with H, and are common acids like HNO₃, H₂SO₄, etc.):
→ Use their special acid names (like nitric acid, sulfuric acid, hydrochloric acid, etc.).
→ If it’s H + halogen (F, Cl, Br, I), it’s “hydro[halogen]ic acid”.
→ If it’s H + polyatomic ion ending in “-ate”, it becomes “-ic acid”.
→ If it’s H + polyatomic ion ending in “-ite”, it becomes “-ous acid”.

Also note: H₂O and H₂O₂ are exceptions — they’re water and hydrogen peroxide, not named as acids.

Now let’s solve each:

(1) NO → nitrogen monoxide ✔ (already given)

(2) HNO₃ → nitric acid ✔ (already given)

(3) H₃PO₄ → This is phosphoric acid (common acid, from phosphate PO₄³⁻ → -ic acid)

(4) N₂O₃ → dinitrogen trioxide (two N, three O → prefixes needed)

(5) SiO₂ → silicon dioxide (Si is first, no prefix since 1; O is second, two atoms → di-)

(6) N₂O₅ → dinitrogen pentoxide

(7) HNO₂ → nitrous acid (from nitrite NO₂⁻ → -ous acid)

(8) HBr → hydrobromic acid (H + bromine → hydro[brom]ic acid)

(9) C₄H₈ → tetracarbon octahydride? Wait — actually, this is a hydrocarbon. But according to strict covalent naming: carbon first, then hydrogen → tetracarbon octahydride. However, in real chemistry, we’d call it butene or something, but since this worksheet uses systematic naming, we’ll go with: tetracarbon octahydride. BUT — wait! Hydrocarbons are usually named differently. Let me check the pattern. Actually, looking at other problems, they seem to want systematic covalent names. So yes: tetracarbon octahydride. However, note that sometimes CH₄ is called methane, but here they’re treating all as covalent. Since C₄H₈ has 4 carbons and 8 hydrogens, and both are nonmetals, we name it as: tetracarbon octahydride. But let’s double-check — in many curricula, they might expect “butene” but that’s organic naming. Given the context of this worksheet (naming rules for covalent compounds), we should use prefixes. So: tetracarbon octahydride.

Wait — actually, looking back at the example: H₂O₂ was named dihydrogen dioxide. So they are using full prefix system even for H-containing compounds unless it’s an acid. But H₃PO₄ is an acid, so we name it as acid. C₄H₈ does NOT start with H as the first element? Wait — formula is written as C₄H₈, so carbon is first. So it’s not an acid. So yes: tetracarbon octahydride.

But hold on — in standard IUPAC, we don’t name hydrocarbons this way. However, since this is a basic naming worksheet focusing on covalent rules, and they included C₄H₈, we must apply the rule literally. So:

→ First element: carbon → 4 atoms → tetracarbon
→ Second element: hydrogen → 8 atoms → octahydride
→ Name: tetracarbon octahydride

But I recall that sometimes hydrogen is treated specially. Let me think — in the example, H₂O₂ was named dihydrogen dioxide, meaning hydrogen was treated as the first element because it was written first. In C₄H₈, carbon is written first, so carbon is first element. So yes, tetracarbon octahydride.

However, I’ve seen some worksheets treat any compound with H and nonmetal as potentially acidic, but C₄H₈ is not acidic. So we stick with covalent naming.

Actually, let me check online or standard practice — no, for this level, if it’s not starting with H and isn’t a known acid, we use covalent naming. So C₄H₈ = tetracarbon octahydride.

But wait — another thought: in some systems, they might write it as "octahydrotetracarbon" but no, the rule says first element keeps name, second gets -ide. Hydrogen becomes hydride. So yes.

I think it's correct.

(10) H₂SO₃ → sulfurous acid (from sulfite SO₃²⁻ → -ous acid)

(11) CCl₄ → carbon tetrachloride (C is first, 1 atom → no prefix; Cl is second, 4 atoms → tetrachloride)

(12) HC₂H₃O₂ → acetic acid (this is the formula for acetic acid, also written as CH₃COOH. It’s a common acid, so we use its common name: acetic acid. Sometimes called ethanoic acid, but in high school chem, it’s acetic acid.)

Note: The formula is often written as CH₃COOH, but here it’s HC₂H₃O₂, which is the same thing. Yes, acetic acid.

(13) HClO₄ → perchloric acid (from perchlorate ClO₄⁻ → -ic acid)

(14) HClO₃ → chloric acid (from chlorate ClO₃⁻ → -ic acid)

(15) H₂SO₄ → sulfuric acid (from sulfate SO₄²⁻ → -ic acid)

(16) H₂S → hydrosulfuric acid (H + sulfur → hydro[sulfur]ic acid; note: not “sulfuric” — that’s for SO₄)

(17) HI → hydroiodic acid (H + iodine → hydro[iod]ic acid)

(18) H₂O₂ → hydrogen peroxide (exception given in instructions: H₂O and H₂O₂ are exceptions — don’t name as acids or covalent with prefixes? Wait, the instruction says: “Exception: H₂O and H₂O₂” — and in the example, they named H₂O₂ as dihydrogen dioxide? No, look back:

In the box: “Ex: name the following compound -H₂O₂” and they showed steps and got “dihydrogen dioxide”. But then it says “Exception: H₂O and H₂O₂” — wait, that seems contradictory.

Let me read carefully:

“Covalent compounds- consist of nonmetal only.
If chemical formula starts with H- it’s an acid; find its name or formula in the Acids List.
Exception: H₂O and H₂O₂”

Then below: “If chemical formula consist of 2 nonmetals only- use the following naming rules. Ex: name the following compound -H₂O₂” and they did dihydrogen dioxide.

So the exception means: even though H₂O and H₂O₂ start with H, they are NOT named as acids — instead, they are named as covalent compounds using the prefix system.

So for H₂O₂, it’s dihydrogen dioxide (as shown in example).

Similarly, H₂O would be dihydrogen monoxide, but commonly water.

So for (18) H₂O₂ → dihydrogen dioxide (as per example)

But wait, in reality, we call it hydrogen peroxide, but according to this worksheet’s rule, since it’s listed as an exception to the acid rule, and they demonstrated naming H₂O₂ as dihydrogen dioxide, we should follow that.

Looking at the example: they explicitly named H₂O₂ as dihydrogen dioxide. So for consistency, we do the same.

So (18) H₂O₂ → dihydrogen dioxide

(19) Cl₂F → dichlorine monofluoride (Cl first, 2 atoms → di; F second, 1 atom → monofluoride)

(20) N₂H₄ → dinitrogen tetrahydride (N first, 2 → di; H second, 4 → tetrahydride)

(21) Cl₂O₇ → dichlorine heptoxide (Cl: 2 → di; O: 7 → heptoxide)

(22) HCl → hydrochloric acid (H + chlorine → hydro[chlor]ic acid)

(23) NH₃ → nitrogen trihydride? But commonly ammonia. However, according to covalent naming: nitrogen first (1 atom, no prefix), hydrogen second (3 atoms → trihydride) → nitrogen trihydride. But again, in many contexts, it’s ammonia. But this worksheet seems to want systematic names. Looking at the example, they didn’t use common names except for acids. For NH₃, it’s not an acid, so covalent naming: nitrogen trihydride.

But I recall that in some curricula, NH₃ is accepted as ammonia, but here since they’re teaching prefix system, probably nitrogen trihydride.

Wait, let’s see if there’s a pattern. In the list, they have HBr, HI, etc. as acids, but NH₃ doesn’t start with H as the first element? Formula is NH₃, so nitrogen is first. So not an acid. So covalent: nitrogen trihydride.

However, I think in most high school worksheets, they accept "ammonia" for NH₃, but strictly by the rules given, it should be nitrogen trihydride. To be safe, let's follow the rule: since it's two nonmetals, and not starting with H (wait, it does start with N, not H), so covalent naming applies.

Formula is NH₃ — nitrogen is first element. So: nitrogen (no prefix for 1) + hydride with prefix for 3 → trihydride → nitrogen trihydride.

But I have a doubt because ammonia is so common. Let me check the other compounds. For example, CH₄ would be carbon tetrahydride, but often called methane. Here they have C₄H₈, which we're calling tetracarbon octahydride, so consistent.

So I'll go with nitrogen trihydride.

(24) H₄SiO → silicic acid? This is orthosilicic acid, but commonly just silicic acid. Since it starts with H and is an acid (silicon-based acid), we name it as silicic acid. From silicate SiO₄⁴⁻ → -ic acid.

Yes, silicic acid.

(25) Cl₂O → dichlorine monoxide

(26) PCl₅ → phosphorus pentachloride (P is first, 1 atom → no prefix; Cl is second, 5 → pentachloride)

(27) HF → hydrofluoric acid (H + fluorine → hydro[fluor]ic acid)

(28) Cl₂O → already did? Wait, (25) is Cl₂O, (28) is also Cl₂O? That can't be. Let me check the original image.

Looking back at user input:

(25) Cl₂O: _______________
(26) PCl₅ _______________
(27) HF _______________
(28) Cl₂O _______________

Oh, duplicate? Probably a typo in the worksheet. But (25) and (28) are both Cl₂O. So same answer: dichlorine monoxide.

Perhaps it's a mistake, but we'll answer both as dichlorine monoxide.

(29) CS₂ → carbon disulfide (C first, 1 → no prefix; S second, 2 → disulfide)

(30) H₂CO₃ → carbonic acid (from carbonate CO₃²⁻ → -ic acid)

(31) SF₄ → sulfur tetrafluoride (S first, 1 → no prefix; F second, 4 → tetrafluoride)

(32) SiC → silicon carbide (this is a compound where we don't use prefixes; it's traditionally called silicon carbide. According to covalent rules: silicon first, carbon second → monocarbon? But usually, for such compounds, we drop mono and just say silicon carbide. In fact, SiC is always called silicon carbide, not monocarbon monosilicon or something. So we'll go with silicon carbide.)

Check the rule: for second element, take root and add -ide. Carbon → carbide. And since only one of each, no prefixes needed? The rule says: "add prefixes which will show how many atoms", but for 1, we omit mono on first element, and for second element, if it's 1, we still say mono? But in practice, for binary compounds like CO, it's carbon monoxide, not carbon oxide. For SiC, it's conventionally silicon carbide without prefixes.

Looking at the example: they didn't have a case with 1 and 1 except possibly, but in NO, they said nitrogen monoxide, so they used mono for oxygen.

For SiC: silicon is first, 1 atom → no prefix. Carbon is second, 1 atom → should be monocarbide? But that's not standard. Actually, in many sources, SiC is named silicon carbide, implying no prefixes when both are 1, but the rule might require mono for the second element.

This is ambiguous. Let me think: in the rule, step (c) says "add prefixes which will show how many atoms", and in the example for H₂O₂, they used di for both. For NO, they used mono for oxygen.

So for SiC: silicon (1, no prefix) + carbon (1, so monocarbide?) → silicon monocarbide? But that's not common.

I recall that for some compounds like CO, it's carbon monoxide, so mono is used for the second element if it's 1. Similarly, for SiC, it should be silicon monocarbide? But I've never heard that.

Upon second thought, in introductory chemistry, SiC is simply called silicon carbide, and prefixes are omitted when not necessary, but the rule might insist.

To be consistent with the worksheet's approach, since they used "monoxide" for NO, they likely expect "monocarbide" for SiC. But let's see if there's another example.

In the list, (29) CS₂ is carbon disulfide — they didn't say monocarbon, so for first element 1, no prefix; for second, if >1, prefix; if =1, mono.

For SiC, second element is 1, so should be monocarbide.

But I think in practice, it's accepted as silicon carbide. However, to follow the rule strictly as taught in the example, for NO they said nitrogen monoxide, so for SiC, it should be silicon monocarbide.

But let's confirm with a reliable source in my mind: actually, the IUPAC name for SiC is silicon carbide, and prefixes are not used for 1:1 ratios in such cases, but for teaching purposes, some worksheets might expect silicon monocarbide.

Given that this is a basic worksheet, and they have NO as nitrogen monoxide, I think they want silicon monocarbide.

But I'm unsure. Let me look at (33) P₂S₅ — that will be diphosphorus pentasulfide, so prefixes are used.

For SiC, since both are 1, and to be consistent, perhaps silicon monocarbide.

However, I found a better way: in many textbooks, for binary covalent compounds, if the first element has only one atom, no prefix, and for the second element, if it has one atom, "mono" is used. For example, CO is carbon monoxide, not carbon oxide. Similarly, SiC should be silicon monocarbide.

Yes, that makes sense. So (32) SiC → silicon monocarbide

(33) P₂S₅ → diphosphorus pentasulfide

(34) F₂O₂ → difluorine dioxide? But F₂O₂ is not common; usually it's OF₂ or something. Formula is F₂O₂, so fluorine first, 2 atoms → difluorine; oxygen second, 2 atoms → dioxide → difluorine dioxide.

But note: sometimes it's written as O₂F₂, but here it's F₂O₂, so fluorine is first element.

So difluorine dioxide.

Now, let's compile all answers:

(3) H₃PO₄ → phosphoric acid
(4) N₂O₃ → dinitrogen trioxide
(5) SiO₂ → silicon dioxide
(6) N₂O₅ → dinitrogen pentoxide
(7) HNO₂ → nitrous acid
(8) HBr → hydrobromic acid
(9) C₄H₈ → tetracarbon octahydride
(10) H₂SO₃ → sulfurous acid
(11) CCl₄ → carbon tetrachloride
(12) HC₂H₃O₂ → acetic acid
(13) HClO₄ → perchloric acid
(14) HClO₃ → chloric acid
(15) H₂SO₄ → sulfuric acid
(16) H₂S → hydrosulfuric acid
(17) HI → hydroiodic acid
(18) H₂O₂ → dihydrogen dioxide (per example)
(19) Cl₂F → dichlorine monofluoride
(20) N₂H₄ → dinitrogen tetrahydride
(21) Cl₂O₇ → dichlorine heptoxide
(22) HCl → hydrochloric acid
(23) NH₃ → nitrogen trihydride
(24) H₄SiO₄ → silicic acid
(25) Cl₂O → dichlorine monoxide
(26) PCl₅ → phosphorus pentachloride
(27) HF → hydrofluoric acid
(28) Cl₂O → dichlorine monoxide (same as 25)
(29) CS₂ → carbon disulfide
(30) H₂CO₃ → carbonic acid
(31) SF₄ → sulfur tetrafluoride
(32) SiC → silicon monocarbide
(33) P₂S₅ → diphosphorus pentasulfide
(34) F₂O₂ → difluorine dioxide

I think that's all. Now, for (9) C₄H₈, I'm still a bit unsure, but based on the rules, it should be tetracarbon octahydride. Similarly for (20) N₂H₄, dinitrogen tetrahydride.

For (23) NH₃, nitrogen trihydride is correct by the rules, though commonly ammonia.

For (32) SiC, silicon monocarbide is consistent with the prefix system.

Now, let's write the final answers in order.

Final Answer:
(3) phosphoric acid
(4) dinitrogen trioxide
(5) silicon dioxide
(6) dinitrogen pentoxide
(7) nitrous acid
(8) hydrobromic acid
(9) tetracarbon octahydride
(10) sulfurous acid
(11) carbon tetrachloride
(12) acetic acid
(13) perchloric acid
(14) chloric acid
(15) sulfuric acid
(16) hydrosulfuric acid
(17) hydroiodic acid
(18) dihydrogen dioxide
(19) dichlorine monofluoride
(20) dinitrogen tetrahydride
(21) dichlorine heptoxide
(22) hydrochloric acid
(23) nitrogen trihydride
(24) silicic acid
(25) dichlorine monoxide
(26) phosphorus pentachloride
(27) hydrofluoric acid
(28) dichlorine monoxide
(29) carbon disulfide
(30) carbonic acid
(31) sulfur tetrafluoride
(32) silicon monocarbide
(33) diphosphorus pentasulfide
(34) difluorine dioxide