Chemical Compound Classification and Nomenclature

Hydrides: Definition and Types

Hydrides are chemical compounds consisting of a metal or non-metal element bonded with hydrogen. They are broadly categorized into metal hydrides and non-metal hydrides.

Metal Hydrides

Metal hydrides are formed when hydrogen combines with a metal. In their nomenclature, the word "hydride" is written first, followed by the name of the metal. For example:

• NaH = Sodium Hydride

Non-metal Hydrides

Non-metal hydrides are formed when hydrogen combines with a non-metal. Their naming can follow traditional nomenclature or special common names. The general formula varies depending on the group the non-metal belongs to and its oxidation state. Examples include:

• NH₃ = Ammonia / Nitrogen Hydride (III)
• CH₄ = Methane / Carbon Hydride (IV)
• PH₃ = Phosphine / Phosphorus Hydride (III)
• SiH₄ = Silane / Silicon Hydride (IV)

Hydride Acids (Binary Acids)

Hydride acids, also known as binary acids, are typically formed by non-metals from Groups 16 (VIA) and 17 (VIIA) of the periodic table. When naming these compounds in their gaseous state, the name of the non-metal is followed by the suffix "-ide" and then "hydrogen." Alternatively, the non-metal root is combined with "hydro-" and the suffix "-ic acid" when dissolved in water.

Examples of gaseous hydride acids:

• HF = Hydrogen Fluoride
• HCl = Hydrogen Chloride
• H₂S = Hydrogen Sulfide
• H₂Se = Hydrogen Selenide

When these compounds are dissolved in water, they are known as:

• Hydrofluoric Acid (from HF)
• Hydrochloric Acid (from HCl)
• Hydrosulfuric Acid (from H₂S)
• Hydroselenic Acid (from H₂Se)

Binary Salts

Binary salts are ionic compounds composed of two elements, typically a metal and a non-metal. Their name is formed by taking the root of the non-metal, adding the suffix "-ide," and then stating the name of the metal. For example:

• NaCl = Sodium Chloride
• AlCl₃ = Aluminum Chloride
• CaS = Calcium Sulfide

Ternary Compounds

Hydroxides

Hydroxides are compounds characterized by the presence of the hydroxide ion (OH^-). They are typically formed by the reaction between a basic oxide and water, or directly from certain alkali metals and water.

To name hydroxides, the word "hydroxide" is written first, followed by the name of the metal. IUPAC nomenclature may include the oxidation state of the metal if it has multiple possible states.

Examples:

• NaOH = Sodium Hydroxide
• Ba(OH)₂ = Barium Hydroxide
• Fe(OH)₂ = Iron(II) Hydroxide or Ferrous Hydroxide
• Fe(OH)₃ = Iron(III) Hydroxide or Ferric Hydroxide

Formation reactions of hydroxides:

• Na₂O + H₂O → 2NaOH
• BaO + H₂O → Ba(OH)₂

Oxoacids (Oxyacids)

Oxoacids, also known as oxyacids, are compounds formed by the reaction of a non-metal oxide (acidic oxide) with water. They contain hydrogen, oxygen, and at least one other element, with at least one hydrogen atom bonded to oxygen.

Examples:

• H₂SO₄ = Sulfuric Acid
• HNO₃ = Nitric Acid

Formation reactions of oxoacids:

• SO₃ + H₂O → H₂SO₄
• N₂O₅ + H₂O → 2HNO₃