Writing and Naming of Inorganic Compounds

CLASSIFICATION AND WRITING FORMULAS OF ORGANIC COMPOUNDS

OBJECTIVES

  • Students will learn to:

    • Recognize and name ionic compounds.

    • Recognize and name covalent compounds.

    • Write chemical formulas for various compounds.

BINARY IONIC COMPOUNDS

Definition

  • A binary compound consists of two elements.

  • Examples include:

    • NaCl (sodium chloride)

    • CO2 (carbon dioxide)

    • NH3 (ammonia)

Characteristics of Binary Ionic Compounds

  • Composed of one metal and one non-metal.

Naming Binary Ionic Compounds

  • Follow these naming rules:

    1. Name the metal first.

    2. Use the stem of the non-metal name and add the suffix -ide.

    • Example: NaF = Sodium fluoride

COMMON NON-METALLIC ELEMENTS

Element

Stem

Name of Ion

Formula of Ion

Bromine

brom-

Bromide

Br-

Carbon

carb-

Carbide

C4-

Chlorine

chlor-

Chloride

Cl-

Fluorine

fluor-

Fluoride

F-

Hydrogen

hydr-

Hydride

H-

Iodine

iod-

Iodide

I-

Nitrogen

nitr-

Nitride

N3-

Oxygen

ox-

Oxide

O2-

Phosphorus

phosph-

Phosphide

P3-

Sulfur

sulf-

Sulfide

S2-

VARIABLE CHARGE METALS

Naming Rule

  • Some metals may form different ions. For example:

    • Iron can form Fe2+ or Fe3+.

    • Naming compounds includes the charge denoted by Roman numerals.

  • Examples:

    • FeCl2 = Iron (II) chloride

    • FeCl3 = Iron (III) chloride

    • CuO = Copper (II) oxide

POLYATOMIC IONS

Definitions

  • Monoatomic Ion: Formed from a single atom.

    • Examples: Cl-, Na+, Ca2+

  • Polyatomic Ion: Formed from a group of atoms.

    • Example: SO4^2- (sulfate)

STABILITY

  • Polyatomic ions maintain their identity in reactions.

  • They are associated with opposite charge ions, not existing as standalone molecules.

COMMON POLYATOMIC IONS

Key Element Present

Formula

Name of Ion

Nitrogen

NO3-

Nitrate

Nitrogen

NO2-

Nitrite

Sulfur

SO4^2-

Sulfate

Sulfur

SO3^2-

Sulfite

Phosphorus

PO4^3-

Phosphate

Hydrogen

H3O+

Hydronium

Hydroxide

OH-

Hydroxide

NAMING IONIC COMPOUNDS WITH POLYATOMIC IONS

Writing Formulas

  1. Enclose polyatomic ions in parentheses if more than one is present.

    • Example: Fe(OH)3 for iron hydroxide.

  2. Identical elemental symbols may appear more than once.

    • Example: NH4NO3 where both ions contain nitrogen (N).

NAMING COMPOUNDS

Ionic Compounds with Polyatomic Ions

  • Follow naming rules:

    • Metal name + polyatomic ion name or

    • Positive polyatomic ion name + negative polyatomic ion name if both are present.

BINARY MOLECULAR COMPOUNDS

Definition

  • Consist only of two non-metallic elements.

Naming Rules

  1. Use numerical prefixes to indicate the number of atoms.

  2. Lower electronegativity element named first, more electronegative second,

    • Example: CO = Carbon monoxide

USAGE OF PREFIXES

Number

Prefix

Example

1

mono-

CO

2

di-

H2F2

3

tri-

NCl3

4

tetra-

S4N4

5

penta-

ClF5

IUPAC SYSTEM

  • Differentiate between cations and anions based on charge.

    • Cations: Monoatomic, Fixed or Variable Oxidation State.

    • Anions: Monoatomic, Polyatomic.

NAMING ACIDS

Binary Acids

  • Hydro + root + -ic acid

    • Example: HCl = Hydrochloric acid

Oxyacids

  • Ends with -ate or -ite.

    • Examples: HNO3 = Nitric acid, HNO2 = Nitrous acid

NAMING BASES AND HYDRATES

  • Bases include M+ and OH-.

  • Hydrates are salts with water molecules.

    • Example: CuSO4 . 5H2O = Copper sulfate pentahydrate

FORMULAS

Compound

Formula

Sodium hydroxide

NaOH

Aluminum oxide

Al2O3

Potassium peroxide

K2O2

Cobaltic phosphate

CoPO4

Magnesium hydride

MgH2

QUESTIONS

  • Students are encouraged to ask questions related to the topic.

REFERENCES

  • Chang, Raymond. General Chemistry, 7th edition, McGraw Hill 2014.

  • Stoker, H. Stephen. Exploring General, Organic and Biological Chemistry, 6th edition, 2013.