Nomenclature

“How Do We Name Compounds?”

Systematic Naming

• Compounds are made up of two or more elements
• Name should tell us how many and what type of atoms
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Metals

Metals

• Qualities of Metals
• Luster – shiny
• Ductile – think making it into wires
• Malleable – hammer it into sheets
• Good conductors of heat and electricity

Transition Metals

Non-metals

Anion

• Negative ion
• Has gained electrons
• Non metals form anions

Cation

• Positive ion
• Formed by losing electrons
• Metals form cations

Ionic Compounds

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• Made of cations and anions
• Metals and nonmetals
• Electrons lost by the cation are gained by the anion

Ionic Compounds

Sodium is cation

1-

Cl

Na +

1+

Chlorine is anion

Charges on Ions

Naming Ions

• Metal ion is written first in both name and formula
• It is named directly from element which formed the ion.
• Usually it is the positive ion or “cation”

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• Transition metals can have more than one type of charge
• Indicate the charge with roman numerals in parenthesis. Iron(II) or Iron(III)
• Exceptions:
• Silver always +1
• Cadmium and Zinc always +2

Name these

• Na ¹⁺
• Ca ²⁺
• Al ³⁺
• Fe ³⁺
• Fe ²⁺
• Pb ²⁺
• Li ¹⁺

• Sodium ion
• Calcium ion
• Aluminum ion
• Iron (III) ion
• Iron (II) ion
• Lead (II) ion
• Lithium ion

Write Formulas for these

• Potassium ion
• Magnesium ion
• Copper (II) ion
• Chromium (IV) ion
• Barium ion
• Mercury (II) ion

• K¹⁺
• Mg²⁺
• Cu²⁺
• Cr⁴⁺
• Ba²⁺
• Hg²⁺

Naming Anions

• Anions are always the same.
• Change the element ending to -- ide
• F^1- Fluorine to Fluoride

Name These

• Cl^1-
• N^3-
• Br ^1-
• O^2-
• I^1-
• Sr²⁺

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• Chloride ion
• Nitride ion
• Bromide ion
• Oxide ion
• Iodide ion
• Strontium ion

Write These�

• Sulfide ion
• Iodide ion
• Phosphide ion
• Strontium ion

• S^2-
• I^1-
• P^3-
• Sr²⁺

Polyatomic Ions

• Tightly bound groups of atoms acting as a single ion.
• Names given in table on back of PT.
• Most are anions that contain oxygen. Names end in –ate (one more O), or –ite (one less O).
• SO₃^2- = sulfite; SO₄^2- = sulfate
• Exceptions: Ammonium cation NH₄⁺¹, Cyanide CN^-, and hydroxide OH^-

Naming Binary Ionic Compounds

• 2 elements involved
• Ionic – metal (cation) and a non-metal (anion)
• Naming is easy with elements in representitive groups
• NaCl = Na⁺ Cl^- = sodium chloride
• MgBr₂ = Mg²⁺Br^- = magnesium bromide

You MUST charge balance EVERYTIME you write a formula for an ionic compound!!!

Naming Binary Ionic Compounds

• The problem comes with the transition metals.
• Need to figure out their charges
• All ionic compounds will have a neutral charge
• Same number of + and – charges
• Use the anion to determine the charge on the positive ion.

Naming Binary Ionic Compounds

• Try naming these
• KCl
• Na₃N
• CrN
• ScP
• PbO
• PbO₂
• Na₂Se

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• Potassium chloride
• Sodium nitride
• Chromium (III) nitride
• Scandium (III) phosphide
• Lead (II) oxide
• Lead (IV) oxide
• Sodium selenide

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Ternary Ionic Compounds

• Will have polyatomic ions
• At least 3 elements
• Back of PT
• Name these
• NaNO₃
• CaSO₄
• CuSO₃
• (NH₄)₂O

• LiCN
• Fe(OH)₃
• (NH₄)₂CO₃
• NiPO₄

• Sodium nitrate
• Calcium sulfate
• Copper (II) sulfite
• Ammonium oxide

• Lithium cyanide
• Iron (III) hydroxide
• Ammonium carbonate
• Nickel (III) phosphate

Writing Formulas�(charge balancing)�

• Net charge must add to zero. Get charges of cation/anion
• Balance the charges
• Put polyatomics in parenthesis

Writing Formulas

• Write formula for calcium chloride
• Calcium is Ca²⁺
• Chloride is Cl^1-
• Ca⁺²Cl^-1 would have a +1 charge
• Need another Cl^1-

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• Ca⁺²Cl₂^-1 = CaCl₂

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Writing Formulas

• Crisscross method

Ca²⁺ Cl^1-

CaCl₂

No need to write the one

Iron (III) sulfide

Calcium chloride

Fe ₂ S₃

Fe ³⁺ S^2-

Fe₂S₃

Write Formulas for These

• Lithium sulfide
• Tin (II) oxide
• Tin (IV) oxide
• Magnesium fluoride
• Copper (II) sulfate
• Iron (III) phosphide
• Iron (III) sulfide
• Ammonium chloride
• Ammonium sulfide

• Li₂S
• SnO
• SnO₂
• MgF₂
• CuSO₄
• FeP
• Fe₂S₃
• (NH₄)Cl
• (NH₄)₂S

Things to Look For

• If cations have ( ), the roman numeral is their charge.
• If anions end in –ide they probably are off the periodic table.
• If anion ends in –ate or –ite it is a polyatomic ion

Types of Reactions

• Millions of reactions
• Too many to remember
• They fall into several categories
• We will focus on Double Replacement in today’s lab

Double Replacement

• Two things replace each other
• Reactants must be two ionic compounds or acids.
• Usually in aqueous solution
• NaOH + FeCl₃ 🡪
• The positive ions change place
• NaOH + FeCl₃ 🡪 Fe⁺³OH^- +Na⁺¹Cl^-1
• NaOH + FeCl₃ 🡪 Fe(OH)₃ + NaCl

Double Replacement

• Will only happen if one of the products
• Doesn’t dissolve in water and forms a solid
• (look at solubility rules)
• Or is a gas that bubbles out
• Or is a covalent compound usually water

Potassium iodide

After adding lead nitrate

2KI_(aq) + Pb(NO₃)_{2 (aq)} 🡪 2KNO_3(aq) + PbI_{2 (s)}

PbI₂ lead (II) iodide is insoluble

General Rules for the Water Solubilities of Common Ionic Compounds

• Compounds that are mostly soluble:
• All nitrates
• Alkali metal (group 1A) and ammonium compounds
• Chlorides, bromides, and iodides, except for those of Pb²⁺, Ag⁺, Hg²⁺
• Sulfates except for those of Sr²⁺, Ba²⁺, Pb²⁺, and Hg²⁺
• CaSO₄ is slightly soluble

General Solubility Rules

• Compounds that are mostly insoluble:
• Carbonates, hydroxides, and sulfides, except for ammonium compounds and those of the group 1A metals. (The hydroxides and sulfides of Ca²⁺, Sr²⁺, and Ba²⁺ are slightly to moderately soluble.)

EXAMPLE 1

• Na₂S(aq) + Cd(NO₃)₂(aq) 🡪

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• What will the products be?
• Na₂S(aq) + Cd(NO₃)₂(aq) 🡪 CdS(s) + NaNO₃(aq)
• Double replacement occurs because cadmium sulfide is insoluable – forms solid and no longer participates in reaction.

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• Balanced equation?
• Na₂S(aq) + Cd(NO₃)₂(aq) 🡪 CdS(s) + 2NaNO₃(aq)

Ionic Equations – Showing the Ions

• Ionic equations show all free ions (ions that are free to move around when dissolved in a liquid – usually water).
• Ions that are not directly involved in the reaction are spectator ions.
• A net ionic equation is one in which spectator ions are NOT shown.

EXAMPLE 2

• NaOH (aq) + MgSO₄ (aq) 🡪

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• What will the products be?
• NaOH (aq) + MgSO₄ (aq) 🡪 Mg(OH)₂ (s) + Na₂SO₄ (aq)
• Double replacement occurs because hydroxides of 2A metals are insoluble.

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• Balanced Chemical Equation?
• 2NaOH (aq) + MgSO₄ (aq) 🡪 Mg(OH)₂ (s) + Na₂SO₄ (aq)

Ionic Equations of Example 2

• 2NaOH (aq) + MgSO₄ (aq) 🡪 Mg(OH)₂ (s) + Na₂SO₄ (aq)

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• Ionic Equation
• 2Na⁺ + 2OH^- + Mg²⁺ + SO₄^2- 🡪 Mg(OH)₂ (s) + 2Na⁺¹ + SO₄^2-

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• Net Ionic Equation (w/o spectator ions)
• 2Na⁺ + 2OH^- + Mg²⁺ + SO₄^2- 🡪 Mg(OH)₂ (s) + 2Na⁺¹ + SO₄^2-
• 2OH^- + Mg²⁺ 🡪 Mg(OH)₂ (s)