Naming Chemical Compounds Notes

Naming Chemical Compounds

Types of Inorganic Compounds

Four main types:
- Ionic
- Molecular
- Acids and Bases
- Hydrates

Predicting Ionic Charges

Atoms gain or lose electrons to achieve the electron configuration of the nearest noble gas.
Group 1A atoms form 1+ ions.
Group 2A atoms form 2+ ions.
Group 7A atoms form 1- ions.
Group 6A atoms form 2- ions.

Periodic Table and Ion Formation

Illustrates common ion charges based on group number.
Examples include: $Na^+$ , $Mg^{2+}$ , $Al^{3+}$ , $O^{2-}$ , $F^{-}$

Ionic Compounds

Composed of positively charged ions (cations) and negatively charged ions (anions).
Cations are generally metal ions, and anions are typically nonmetal ions.
Formed through combinations of metals and nonmetals.
Molecular compounds are generally composed of nonmetals only.

Empirical Formulas for Ionic Compounds

Only empirical formulas can be written for most ionic compounds.
Total positive charge equals the total negative charge.
Examples:
- $NaCl$ ( $Na^+$ and $Cl^-$ )
- $BaCl_2$ ( $Ba^{2+}$ and $Cl^-$ )
- $Mg3N2$ ( $Mg^{2+}$ and $N^{3-}$ )

Criss-Cross Method

Used to determine the correct subscripts in an ionic compound formula.
Examples:
- $Ba^{2+}$ and $Cl^-$
- $Al^{3+}$ and $O^{2-}$
- $Mg^{2+}$ and $N^{3-}$
- $Mg^{2+}$ and $O^{2-}$

Naming Ionic Compounds: Positive Ions (Cations)

Cations formed from metal atoms have the same name as the metal.
If a metal can form cations of differing charges, the charge is indicated by a Roman numeral in parentheses (Stock system).
- Example: $Fe^{2+}$ is Iron(II), $Fe^{3+}$ is Iron(III).
Cations formed from nonmetal atoms have names that end in -ium:
- $NH_4^+$ : ammonium ion

Naming Ionic Compounds: Negative Ions (Anions)

Monatomic anions have names formed by dropping the ending of the element name and adding -ide.

Polyatomic Anions

Polyatomic anions containing oxygen have names ending in -ate or -ite.
- Examples:
  - $NO_2^-$ : nitrite
  - $NO_3^-$ : nitrate
  - $SO_3^{2-}$ : sulfite
  - $SO_4^{2-}$ : sulfate
  - $ClO_2^-$ : chlorite
  - $ClO_3^-$ : chlorate
  - $ClO^-$ : hypochlorite
  - $ClO_4^-$ : perchlorate
  - $PO_4^{3-}$ : phosphate
  - $CO_3^{2-}$ : carbonate

Anions Derived by Adding H+

Named by adding hydrogen or dihydrogen as a prefix.
- Examples:
 - $HCO_3^-$ : hydrogen carbonate
 - $HPO_4^{2-}$ : hydrogen phosphate
 - $HSO_4^-$ : hydrogen sulfate
 - $H2PO4^-$ : dihydrogen phosphate

Common Ions and Their Related Acids

Table of common ions, their formulas, and related acids:
- Ammonium: NH_4^+$
- Hydronium: H_3O^+$
- Peroxide: $O_2^{2-}$
- Hydroxide: OH^-$
- Acetate: CH_3COO^-$
- Cyanide: CN^-$
- Azide: N_3^-$
- Carbonate: $CO_3^{2-}$
- Bicarbonate: HCO_3^-$
- Nitrate: NO_3^-$
- Nitrite: NO_2^-$
- Sulfate: SO_4^{2-}
- Hydrogen sulfate: HSO_4^-$
- Sulfite: $SO_3^{2-}$
- Hydrogen sulfite: HSO_3^-$
- Phosphate: PO_4^{3-}
- Hydrogen phosphate: HPO_4^{2-}
- Dihydrogen phosphate: H2PO4^-$
- Perchlorate: ClO_4^-$
- Chlorate: ClO_3^-$
- Chlorite: ClO_2^-$
- Hypochlorite: ClO^-$
- Chromate: $CrO_4^{2-}$
- Dichromate: $Cr2O7^{2-}$
- Permanganate: MnO_4^-$

Naming Ionic Compounds

The cation name is followed by the anion name.
If there are more than one polyatomic ions, the ion formula is placed in parentheses followed by a subscript.
- Examples:
  - BaBr_2: barium bromide
  - Al(NO3)3: aluminum nitrate
  - CuCO_3: copper (II) carbonate (or cupric carbonate)

Examples of Ionic Compound Names

CrCl_3
NH4NO3
Fe2(SO4)_3
Ni(ClO4)2
Na3PO4
Ca(H2PO4)_2

Naming Binary Molecular Compounds

The element farthest to the left in the periodic table is usually written first.
If both elements are in the same group, the lower one is named first.
The second element is given an -ide ending.
Greek prefixes indicate the number of atoms of each element. Mono- is not used with the first element. If the prefix ends in a or o and the element name begins with a vowel, the a or o is often dropped.

Examples of Binary Molecular Compounds

NF_3
P2O5
BrCl_5
S2F{10}

Greek Prefixes

one: mono-
two: di-
three: tri-
four: tetra-
five: penta-
six: hexa-
seven: hepta-
eight: octa-
nine: nona-
ten: deca-

Acids and Bases: Acids

Acid: A substance that yields hydrogen ions (H^+) when dissolved in water.
Acids based on anions whose names end in -ide have the hydro- prefix and an -ic ending.
- Example: hydrogen chloride becomes hydrochloric acid.

Examples of Acids Based on -ide Anions

Cl^- $(chloride) →$ HCl (hydrochloric acid)
F^- $(fluoride) →$ HF (hydrofluoric acid)
S^{2-} $(sulfide) →$ H_2S (hydrosulfuric acid)

Acids Based on -ate or -ite Anions

-ate anions have associated acids with an -ic ending, while -ite anions have acids with an -ous ending.
- NO2^- $(nitrite) →$ HNO2 (nitrous acid)
- NO3^- $(nitrate) →$ HNO3 (nitric acid)
- SO3^{2-} $(sulfite) →$ H2SO_3 (sulfurous acid)
- SO4^{2-} $(sulfate) →$ H2SO_4 (sulfuric acid)
- PO4^{3-} $(phosphate) →$ H3PO_4 (phosphoric acid)
- CO3^{2-} $(carbonate) →$ H2CO_3 (carbonic acid)

Hypo and Per Prefixes

Hypo- comes from the Greek word for “under.”
Per- is Latin for “all over,” suggesting the element's ability to combine with oxygen is fully satisfied.

Anion to Acid Examples

Hypochlorite, ClO^- $→ Hypochlorous acid,$ HClO
Chlorite, ClO2^- $→ Chlorous acid,$ HClO2
Chlorate, ClO3^- $→ Chloric acid,$ HClO3

Naming Acids with Multiple Hydrogens

If all hydrogens are not removed, indicate the number of hydrogens present.
- Example: H3PO4 $(phosphoric acid) →$ H2PO4^- $(sodium dihydrogen phosphate) →$ HPO4^{2-} $(sodium hydrogen phosphate) →$ PO4^{3-} (sodium phosphate)

Bases

Bases yield hydroxide ions (OH^-) when dissolved in water.
Examples:
- Sodium hydroxide, NaOH $:$ NaOH(s) + H_2O(l) \rightarrow Na^+(aq) + OH^-(aq)
- Potassium hydroxide, KOH
- Barium hydroxide, Ba(OH)_2
- Ammonia, NH3 $:$ NH3(g) + H2O(l) \rightarrow NH4^+(aq) + OH^-(aq)

Hydrates

Ionic compounds with water molecules incorporated into their crystal structure.
- BaCl2 \cdot 2H2O: barium chloride dihydrate
- MgSO4 \cdot 7H2O: magnesium sulfate heptahydrate (Epsom salt)
- Na2CO3 \cdot 10H_2O: sodium carbonate decahydrate (washing soda)
- Na2B4O7 \cdot 10H2O: sodium tetraborate decahydrate (borax)

Example of Hydrate

CoCl2\cdot6H2O $(hydrated cobalt chloride) →$ CoCl_2 (anhydrous cobalt chloride)

Organic Compounds

Carbon-based compounds.
Simplest are hydrocarbons.
- Alkanes: CnH{2n+2}, no carbon-carbon double bonds.
- Alkenes: CnH{2n}, at least one carbon-carbon double bond.
- Alkynes: CnH{2n-2}, at least one carbon-carbon triple bond.

Alkanes Examples

Methane: CH_4
Ethane: C2H6
Propane: C3H8
Butane: C4H{10}
Pentane: C5H{12}
Hexane: C6H{14}
Heptane: C7H{16}
Octane: C8H{18}
Nonane: C9H{20}

Methane and Ethane Structures

Methane (CH_4): A central carbon atom bonded to four hydrogen atoms.
Ethane (C2H6): Two carbon atoms bonded to each other, each also bonded to three hydrogen atoms.
Line-angle formulas do not show carbon or hydrogen labels.
Condensed structural formulas:
- Propane: CH3CH2CH_3
- Butane: CH3CH2CH2CH3
- Pentane: CH3CH2CH2CH2CH_3

Functional Groups

Replace -H with a group.
Hydroxyl (-OH): alcohol (e.g., methanol, H_3C-OH)
Amino (-NH2): amine (e.g., methyl amine, H3C-NH2)
Carboxyl (-COOH): carboxylic acid (e.g., acetic acid/ethanoic acid, H_3C-C-OH$$)