Unit 6: Nomenclature Inorganic and Organic Molecules

Polyatomic Ions (Abridged)

• Polyatomic ions consist of several atoms covalently bonded together and, as a unit, have gained or lost electrons.
• Think of it as a molecule with a charge.

*Note: Many polyatomic ions exist, but you are only required to memorize the ones on this list.

Oxyanions

A mnemonic to help with this section: Nick Brad the Camel ate a Clam for Supper in Phoenix.

• Vowels = Charge

Hydrogen-Containing Oxyanions

• The hydrogen ion is $H^{1+}$, thus adding it to an oxyanion would change the charge of the new ion to be one more positive, in addition to adding the extra atom of hydrogen.
• The name of the ion now would include "hydrogen."
• Sometimes, you will see the prefix "bi" used in place of "hydrogen," thus both would be correct.
  • $HCO_3^{1-}$: carbonate is now "hydrogen carbonate" or "bicarbonate"
  • $HSO_4^{1-}$: sulfate is now "hydrogen sulfate" or "bisulfate"

Other Common Ions

• $OH^{1-}$: hydroxide
• $MnO_4^{1-}$: permanganate
• $CN^{1-}$: cyanide
• $C<em>2H</em>3O<em>2^{1-}$ or $CH</em>3COO^{1-}$: acetate
• $NH_4^{1+}$: ammonium

Expected Demonstrations

• Write the formula when given the name.
• Write the name (spelled correctly) when given the formula.
• Identify if a polyatomic ion is present (or not) in a chemical formula.

Vodcast: Naming Molecular Compounds

• Bond between two nonmetals
  • 3 easy steps!
    1. Name the first element.
    2. Name the second element, but change the suffix to -ide.
    3. Use prefixes to tell how many of each atom are present in the compound (except omit mono- prefix on the 1st element's name).

Note: Drop the vowel of the prefix (usually) when there are two vowels together.

Nomenclature of Molecular Compounds Worksheet (nonmetal and nonmetal)

• Rules for naming molecular compounds:
  1. Name first element
  2. Name second element but change suffix to -ide
  3. Use prefix to tell how many of each atom are present in the compound

• Name the following compounds (#1-13)

  1. $AsCl_3$ Arsenic trichloride
  2. $N_2O$ dinitrogen monoxide
  3. $P<em>2O</em>5$ diphosphorus pentoxide
  4. $XeF_6$ Xenon hexafluoride
  5. $SF_6$ Sulfur hexafluoride
  6. $NO_3$ Nitrogen trioxide
  7. $SiO_2$ Silicon dioxide
  8. $BF_3$ Boron trifluoride
  9. $N<em>2O</em>5$ dinitrogen pentoxide
  10. $SO_2$ Sulfur dioxide
  11. $CH_4$ Carbon tetrahydride
  12. $SeCl_2$ Selenium dichloride
  13. $CO$ Carbon monoxide

• Write the formulas for the following (#14-26)

  14. phosphorus trichloride $PCl_3$
  15. nitrogen monoxide $NO$
  16. carbon tetrafluoride $CF_4$
  17. dinitrogen pentoxide $N<em>2O</em>5$
  18. sulfur trioxide $SO_3$
  19. dinitrogen tetroxide $N<em>2O</em>4$
  20. phosphorus pentachloride $PCl_5$
  21. arsenic tribromide $AsBr_3$
  22. dinitrogen trioxide $N<em>2O</em>3$
  23. carbon disulfide $CS_2$
  24. carbon tetrabromide $CBr_4$
  25. phosphorus triiodide $PI_3$
  26. nitrogen dioxide $NO_2$

Vodcast: Binary Ionic Compounds

• "Binary" means there are only 2 elements in the compound
• Ionic compounds have bonds between a METAL and a NONMETAL
  • 2 easy steps!
    1. Cation given first (do not change spelling)
    2. Anion given second (change ending to -ide)
• Example - Practice naming ionic compounds
  • $NaCl$ → Sodium Chloride…
  • $MgF_2$ → Magnesium Fluoride
• Example - Write formulas for the following ionic compounds >
  • Calcium nitride $→ Ca^{+2}N^{-3} → Ca<em>3N</em>2$
  • Aluminum sulfide $→ Al^{+3}S^{-2} → Al<em>2S</em>3$

Vodcast: Naming Ionic Compounds with Transition Metals

• 3 easy steps!
  1. Name cation (as before)
  2. Give roman numeral after cation (indicates the charge of the metal)
  3. Name anion (as before, with "-ide" ending)

Note: When writing formulas from names with a roman numeral, reverse criss-cross method to determine the charge on the metal. ALSO… verify the anion charge to check for simplification!

• Examples - Name the following compounds:
  • $FeCl_2$ → Iron (II) Chloride
  • $FeCl_3$ → Iron (III) Chloride
  • $CuBr$ → Copper (I) Bromide
• Examples - Write the formula for the following compounds:
  • Copper (I) chloride $→ Cu^{+1}Cl^{-1} → CuCl$
  • Manganese (VII) sulfide $→ Mn^{+7}S^{-2} → Mn<em>2S</em>7$
  • Zinc oxide $→ Zn^{+2}O^{-2} → ZnO$

Naming Binary Ionic Compounds Worksheet (metal and nonmetal/s)

• Examples:
  • $CaO$ calcium oxide
  • $Mg<em>3P</em>2$ magnesium phosphide

NOTE: These compounds consist of a metal and nonmetal that have one ionic charge assigned to them and are found in Groups 1 and 2. We will add three more metals to this category of "Simple Inorganic Compounds," and they are $Al^{3+}$, $Zn^{2+}$, and $Ag^{1+}$

• Name the following compounds:
  • $NaF$ Sodium fluoride
  • $Ca<em>3N</em>2$ Calcium nitride
  • $Li_3P$ Lithium phosphide
  • $ZnS$ Zinc sulfide
  • $K_3P$ Potassium phosphide
  • $Ag_2O$ Silver oxide
  • $AlF_3$ Aluminum fluoride
  • $K_2O$ Potassium oxide
  • $MgS$ Magnesium sulfide
  • $AlCl_3$ Aluminum chloride
  • $NaBr$ Sodium bromide
  • $BaI_2$ Barium iodide
  • $BeCl_2$ Beryllium chloride
• Write the formula for the following compounds: Note: It is good practice to write the predicted charge for each above the words before you write the formula.
  • Sodium sulfide → $Na^{+1}S^{-2} → Na_2S$
  • Magnesium bromide $→ Mg^{+2}Br^{-1} → MgBr_2$
  • Potassium nitride $→ K^{+1}N^{-3} → K_3N$
  • Zinc iodide $→ Zn^{+2}I^{-1} → ZnI_2$
  • Aluminum fluoride $→ Al^{+3}F^{-1} → AlF_3$
  • Strontium iodide $→ Sr^{+2}I^{-1} → SrI_2$
  • Sodium phosphide $→ Na^{+1}P^{-3} → Na_3P$
  • Barium chloride $→ Ba^{+2}Cl^{-1} → BaCl_2$
  • Beryllium phosphide $→ Be^{+2}P^{-3} → Be<em>3P</em>2$
  • Silver oxide $→ Ag^{+1}O^{-2} → Ag_2O$
  • Calcium oxide $→ Ca^{+2}O^{-2} → CaO$
  • Lithium selenide $→ Li^{+1}Se^{-2} → Li_2Se$
  • Barium nitride $→ Ba^{+2}N^{-3} → Ba<em>3N</em>2$
  • Calcium bromide $→ Ca^{+2}Br^{-1} → CaBr_2$
• These compounds consist of two types of elements. What type is always written first? Metal
• When the formulas of the compounds are written correctly, the net (total) charge of the molecule is 0.
• For most of these types of compounds, the metals are located in which groups on the periodic table? (exceptions being aluminum, zinc, and silver) Groups 1 and 2

Naming Ionic Compounds with Transition Metals Worksheet (transition metal and nonmetal/s)

• Examples:
  • $CoO$ cobalt (II) oxide
  • $Ni<em>2P</em>3$ nickel (II) phosphide

NOTE: These compounds consist of a metal and nonmetal where the metals are in the transition family (f groups 3-12). Also included are metals in the p block, such as Pb, Sn, and Ga. Roman numerals indicate the charge of the metal, rather than the number of atoms, and they are only found in the names of a compound, not the formulas.

• Name the following compounds:

  • $CuF$ Copper (I) fluoride
  • $CuF_2$ Copper (II) fluoride
  • $Cu_3P$ Copper (I) phosphide
  • $CdS_2$ Cadmium (II) sulfide
  • $Au_2N$ Gold (I) nitride
  • $PbO$ Lead (II) oxide
  • $PbO_2$ Lead (IV) oxide
  • $Cr<em>2O</em>3$ Chromium (I) oxide
  • $SnS$ Tin (II) sulfide
  • $NiI_3$ Nickel (III) iodide
  • $AuBr$ Gold (I) bromide
  • $Ga<em>2O</em>3$ Gallium (II) oxide
  • $MnCl_7$ Manganese (VII) chloride
  • $TiCl_4$ Titanium (IV) chloride
    It is good practice to write the predicted charge for each above the words before you write the formula.

• Write the formula for the following compounds:

  • Gold (I) sulfide $→ Au^{+1}S^{-2} → Au_2S$
  • Lead (II) bromide $→ Pb^{+2}Br^{-1} → PbBr_2$
  • Lead (IV) nitride $→ Pb^{+4}N^{-3} → Pb<em>3N</em>4$
  • Cobalt (II) iodide $→ Co^{+2}I^{-1} → CoI_2$
  • Iron (III) fluoride $→ Fe^{+3}F^{-1} → FeF_3$
  • Titanium (IV) iodide $→ Ti^{+4}I^{-1} → TiI_4$
  • Manganese (II) phosphide $→ Mn^{+2}P^{-3} → Mn<em>3P</em>2$
  • Nickel (II) chloride $→ Ni^{+2}Cl^{-1} → NiCl_2$
  • Gallium (III) phosphide $→ Ga^{+3}P^{-3} → GaP$
  • Copper (II) oxide $→ Cu^{+2}O^{-2} → CuO$
  • Chromium (IV) oxide $→ Cr^{+4}O^{-2} →CrO_2$
  • Gold (I) chloride $→ Au^{+1}Cl^{-1} → AuCl$
  • Lead (IV) nitride $→ Pb^{+4}N^{-3} → Pb<em>3N</em>4$
  • Scandium (III) sulfide $→ Sc^{+3}S^{-2} → Sc<em>2S</em>3$

• These compounds consist of two types of elements. What type is always written first? Metal

• When the formulas of the compounds are written correctly, the net (total) charge of the molecule is 0.

• For most of these types of compounds, the metals are located in which groups on the periodic table? (exceptions being the p block metals) Groups 3 through 12

• What does the roman numeral indicate in the name of the compound? The charge of the metal.

Vodcast: Naming Ionic Compounds with Polyatomic Ions

• If a formula contains more than 2 different elements (and/or parentheses), there is probably a polyatomic ion. Refer to the list on page 3 of the packet - you should have these memorized by now!

• 3 easy steps!

  1. Cation given first (as before)
  2. Anion given second
  3. Don't change the spelling of a polyatomic ion!

• Example - Practice naming the following compounds:

  • $FeCO_3$ → Iron (II) Carbonate
  • $Fe<em>2(CO</em>3)_3$ → Iron (III) Carbonate
  • $NaBrO_2$ → Sodium Bromite

• Polyatomic ion: 2 or more atoms that act like a single unit (with an overall charge)

• Parenthesis refers to whole ion. Charge should be outside anything in side parenthesis is protected.

• Example - Write the formulas for the following:

  • Sodium bicarbonate. $(Na)^{+1}(HCO<em>3)^{-1}$ → $NaHCO</em>3$
  • Manganese (II) nitrate $(Mn)^{+2}(NO<em>3)^{-1}$ → $Mn(NO</em>3)_2$
  • Ammonium phosphate. $(NH<em>4)^{+1}(PO</em>4)^{-3}$ → $(NH<em>4)</em>3PO_4$

Naming Ionic Compounds with Polyatomic Ions Worksheet (metal and polyatomic Ion) ($NH_4^{+1}$ and an anion)

• Examples:

  • $Co(NO<em>3)</em>2$ cobalt (II) nitrate
  • $Na<em>3PO</em>4$ sodium phosphate
    NOTE: These compounds consist of a metal and polyatomic ion anion. The location of the metal on the periodic table will determine whether a Roman numeral is required in the name or not. (Groups 1 and 2 don't need roman numerals, groups 3-12 do). One exception would be the polyatomic ion $NH_4^{+1}$ takes the place of the metal.

• Name the following compounds.

  • $CaSO_3$ Calcium (II) Sulfite
  • $CuSeO_3$ Copper (I) Selenite
  • $Cu<em>3PO</em>4$ Copper phosphate
  • $NaC<em>2H</em>3O_2$ Sodium Acetate
  • $Al(ClO<em>3)</em>3$ Aluminum Chlorate
  • $LiBrO$ Lithium Hypo Bromite
  • $Ba(MnO<em>4)</em>2$ Barium permanganate
  • $Sc(ClO<em>2)</em>3$ Scandium Chlorite
  • $Zn(NO<em>2)</em>2$ Zinc Nitrite
  • $Mg(BrO<em>4)</em>2$ Magnesium perbromate
  • $Zn(HCO<em>3)</em>2$ Zinc bicarbonate
  • $Mg(CN)_2$ Magnesium cyanide
  • $Ba(OH)_2$ Barium hydroxide
  • $Ti(SO<em>4)</em>2$ Titanium (IV) Sulfate
  • $K<em>2HPO</em>4$ Potassium biphosphate
  • $Sn(CO<em>3)</em>2$ Tin (I) Carbonate

• Write the formula for the following compounds. It is good practice to write the predicted charge for each above the words before you write the formula.

  • Calcium sulfate $→ Ca^{+2}SO<em>4^{-2} → CaSO</em>4$
  • Calcium hydrogen sulfate $→ Ca^{+2}(HSO<em>4)^{-1} → Ca(HSO</em>4)_2$
  • Lead (IV) nitrate $→ Pb^{+4}(NO<em>3)^{-1} → Pb(NO</em>3)_4$
  • Cobalt (II) acetate $→ Co^{+2}(C<em>2H</em>3O<em>2)^{-1} → Co(C</em>2H<em>3O</em>2)_2$
  • Magnesium perchlorate $→ Mg^{+2}(ClO<em>4)^{-1} → Mg(ClO</em>4)_2$
  • Barium hydroxide $→ Ba^{+2}(OH)^{-1} → Ba(OH)_2$
  • Ammonium phosphate $→ (NH<em>4)^{+1}(PO</em>4)^{-3} → (NH<em>4)</em>3(PO_4)$
  • Calcium hypobromite $→ Ca^{+2}(BrO)^{-1} → Ca(BrO)_2$
  • Nickel (II) cyanide $→ Ni^{+2}(CN)^{-1} → Ni(CN)_2$
  • Gallium (III) bromite $→ Ga^{+3}(BrO2)^{-1} → Ga(BrO<em>2)</em>3$
  • Potassium chlorate $→ K^{+1}(ClO<em>3)^{-1} → K(ClO</em>3)$
  • Ammonium carbonate $→ (NH<em>4)^{+1}(CO</em>3)^{-2} → (NH<em>4)</em>2(CO_3)$
  • Aluminum nitrate $→ Al^{+3}(NO<em>3)^{-1} → Al(NO</em>3)_3$
  • Zinc hydrogen phosphate $→ Zn^{+2}(HPO<em>4)^{-2} → Zn(HPO</em>4)$
  • Sodium acetate $→ Na^{+1}(C<em>2H</em>3O<em>2)^{-1} → Na(C</em>2H<em>3O</em>2)$
  • Lead (IV) sulfite $→ Pb^{+4}(SO<em>3)^{-2} → Pb(SO</em>3)_2$

• When the formulas of the compounds are written correctly, the net (total) charge of the molecule is 0.

• When a polyatomic ion is found in a compound, the name of the polyatomic ion Does not change.

Mixed Nomenclature Worksheet

• The type of naming considerations used depends on the first element and where it is located on the periodic table.

  • If all nonmetals, you do not need to consider charges, roman numerals, or polyatomic ions. Rather, prefixes are used for the number of atoms in the molecule.
  • If the first element is a metal, then you will need to consider charges. These may also include roman numerals in the names and polyatomic ions are common.
  • When writing the formulas for ionic compounds (those with metals and/or polyatomic ions), it is advisable to write the charges over the words to help in deciding subscripts of each ion.

• Name the following compounds:

  • $CaSO_3$ Calcium Sulfide
  • $CO_2$ Carbon dioxide
  • $CO$ Carbon monoxide
  • $NaCl$ Sodium Chloride
  • $Al(ClO<em>3)</em>3$ Aluminum Chlorate
  • $Fe<em>3N</em>2$ Iron (II) Nitrogen
  • $Mg(MnO<em>4)</em>2$ Magnesium permanganate
  • $Sc(ClO<em>2)</em>3$ Scandium (II) Chlorite
  • $N<em>2O</em>5$ di Nitrogen Pentoxide
  • $NH_4Br$ ammonium Bromide
  • $K<em>2CO</em>3$ Potassium carbonate
  • $Sn<em>3(PO</em>3)_4$ Tin (IV) Phosphite
  • $Be(BrO<em>3)</em>2$ Beryllium Bromate
  • $Zn(ClO<em>2)</em>2$ Zinc Chlorite
  • $MgO$ Magnesium Oxide
  • $Ca(HSO<em>3)</em>2$ Carbon bisulfite
  • $Mg(OH)_2$ Magnesium hydroxide
  • $SeF_6$ Selenium hexafluoride
  • $Ti(CO<em>3)</em>2$ Titanium (IV) Classrute
  • $S(C<em>2H</em>3O<em>2)</em>2$ Strontium acetate
  • $As<em>2O</em>5$ Diarsenic Pent Oxide
  • $(NH<em>4)</em>2SeO_3$ ammonium Selenite
  • $Ni(MnO<em>4)</em>3$ Nickel (TTI) permanganate
  • $Cr(CN)_2$ Chrumism (II) Cyanide
  • $K_2S$ Pottasiun sulfide
  • $LiHSeO_4$ Lithium biselenate

• Write the formula for the following compounds:
  It is good practice to write the predicted charge for each above the words before you write the formula for all ionic compounds.
  Look at the suffix to help determine the substances that will include a polyatomic ion.
  Look at the prefixes to help determine if the substance is molecular … no metals / charges.

  • Calcium hydrogen sulfate $→ Ca(HSO<em>4)</em>2$
  • Calcium sulfide $→ CaS$
  • Sulfur monoxide $→ SO$
  • Nickel (II) acetate $→ Ni<em>2(C</em>2H<em>3O</em>2)$
  • Carbon tetrachloride $→ CCl_4$
  • Barium hydroxide $→ Ba(OH)_2$
  • Ammonium phosphate $→ (NH<em>4)</em>3PO_4$
  • Nitrogen dioxide $→ NO_2$
  • Beryllium iodide $→ BeI_2$
  • Aluminum fluoride $→ AlF_3$
  • Ammonium oxide $→ NH_4O$
  • Iron (III) carbonate $→ Fe<em>2(CO</em>3)_2$
  • Vanadium (V) sulfate $→ V<em>2(SO</em>4)$
  • Scandium (II) cyanide $→ S<em>2(CN)</em>2$
  • Magnesium bromite $→ Mg(BrO_2)$
  • Potassium hypochlorite $→ K(ClO)$
  • Ammonium nitride $→ (NH<em>4)</em>3N$
  • Silver nitrate $→ Ag(NO_2)$
  • Zinc hydrogen phosphate $→ Zn(HPO_4)$
  • Sodium acetate $→ Na(C<em>2H</em>3O_2)$
  • Lead (IV) sulfite $→ Pb(SO<em>3)</em>2$
  • Dihydrogen monoxide $→ HO$
  • Barium nitrite $→ Ba(NO<em>2)</em>2$
  • Lithium perbromate $→ Li(BrO_4)$
  • Calcium permanganate $→ Ca(MnO<em>4)</em>2$
  • Cadmium (II) sulfide $→ CdS$

IUPAC Nomenclature for Organic Compounds

IUPAC = International Union of Pure and Applied Chemistry, Paris, 1957 (Commission of Nomenclature)

Vodcast: Organic?

• What is an organic molecule?
  • Organic:
    • $CH_4$
    • $CH_2O$
    • $C<em>2H</em>6O$
    • $CH<em>3NH</em>2$
    • $CHCl_3$
  • Inorganic:
    • $CCl_4$
    • $CO$
    • $CO_2$
    • $NaCN$
    • $CaCO_3$

Vodcast: Organic Formulas

• What seems to be the determining characteristic?

  • Organic has at least carbon bonded to hydrogen.
    • Carbon and hydrogen
    • (Carbon based)

• Inorganic - Why are things carbon-based?

  • Organic makes up life.
    • Carbon forms 4 bonds.
    • Forms (strong) covalent bonds

• Molecular (or empirical) formula (3 Hs)

• Lewis line drawing

  • Each corner intersection is a carbon

• Carbon Skeleton C-C-C

  • Just Carbon, No hydrogen.

• Condensed formula $H<em>3CCH</em>2CH_3$

  • What is attached is usually wound

• Structural formula

  • Not shape, any corners

• Perspective drawing.

  • Easier to draw
    *Ball and stick model
  • Clear connection

• each line is a bond

• Carbon form 4 bonds

  • Ex:
    • 1 bond +3 need
    • 2 bond +2
    • 3 bond +1 bonds
      *Space filling model
  • Most Info
  • See overlap

Vodcast: Hydrocarbons

• Hydrocarbons are compounds with only C and H.
• There are four classes:
  • Alkanes (all single bonds):
  • Alkenes (at least one C-C double bond):
  • Alkynes (at least one C-C triple bond):
  • Aromatics (have planar ring structures with alternating single and double bonds - actually have resonance)
    • Resonance hybrid
      *Prefixes are used to indicate the # of Carbons with the longest C-C Chain

Vodcast: Naming Alkanes

1. Find the longest continuous chain of carbons.
2. The prefix represents the number of carbon atoms in the parent chain.
3. The suffix is "-ane" for an alkane (all carbons connected by single bonds).
4. If there is a branch, use a number to indicate where on the parent chain it is attached.
5. Use a prefix to indicate how many carbons make up the branch. (See IUPAC prefixes on page 13)
6. The suffix is "-yl" for each branch.
7. Multiples of the same branch use additional prefixes such as "di-", "tri-", and "tetra-", in addition to a number for each location.
8. If there are several branches, name them in alphabetical order.

• Examples:
  • Hexane
  • 2,3-dimethyl butane
  • 3-methyl pentane
  • 4 ethyl heptane
  • 3,4,5 trimethyl hexane
  • 4-ethyl heptane

Nomenclature - Alkanes Worksheet

Instructions:

1. Circle the longest continuous chain of carbon.
2. Number the parent chain so that the branches have the lowest position number.
3. Use a prefix to indicate two or more identical branches.
4. If there are several branches, name them in alphabetical order.

• Examples:
  • 4-methyl hexane
  • 3-Methyl Butane
  • Pentane
  • 5,6 Dimethyl heptane
  • 3-ethyl 4,4-dimethyl hexane
  • 3-ethyl 5,5-Dimethyl hexane
  • 2-methyl propane
  • 4-methyl hexane
  • 2, dimethyl propare
  • 4,4-dimethyl hexane
  • 4-propyl 11 4-methy ss diethyl Octane

Write the condensed structural formulas for the following compounds.

12. 3,3,6-trimethylnonane

13. 3-ethyl-2-methylpentane

14. 3-ethyl-4-propylheptane

• What is the correct name for this compound?
  • 2 dimethylbutane
  • 3-methy pentane
  • Hexane
  • 3-ethyl-2-methyl Hexane

Lab: Molecular Models

Purpose: You will construct several common molecules using the provided kit. This will support your understanding of molecular shapes and introduce you to how isomers relate to each other.

Key: The following color key will provide you with the correct number of bond sites for each type of atom,

Carbon black
Hydrogen yellow
Oxygen red
Chlorine green

1. A. Build each of the molecules below.

B. Name each of the molecules. Notice that the branch/substituent added to carbon is a halogen, chlorine. Halogens are commonly found in organic molecules. They will be named as branches and the suffix "o" will replace "ine." As an example, fluorine would be named as "fluoro."

• Methane
• Chloromethane
• Trichloromethane

1. Isomers are molecules that have the same condensed formulas, but form different molecular structures. They will have different names.

A. Construct two different molecules for the molecular formula $C<em>2H</em>4Cl_2$.

B. Draw the molecular structure for the two isomers. NOTE: Drawing the 3-D version with wedges and dotted lines would be difficult. You may draw these "flat" with straight lines only.

C. Name the two isomers.

• 1,2; dichloroethane
• 11 dichiara ethane

1. You should be able to make two isomers with $C<em>4H</em>{10}$