Chemical Nomenclature and Atomic Structure Fundamentals

Chemical Nomenclature Rules

This section outlines the basic rules for naming binary and ternary chemical compounds.

Binary Compounds

• Metal Oxides: Oxygen (O) typically has an oxidation state of -2. Formula: M_xO_y (M: metal).
  • Lower oxidation state suffix: -ous.
  • Higher oxidation state suffix: -ic.
• Non-metal Oxides: Oxygen (O) typically has an oxidation state of -2. Formula: NM_xO_y (NM: non-metal).
• Metal Hydrides: Hydrogen (H) has an oxidation state of -1. Formula: MH_x.
• Non-metal Hydrides: Hydrogen (H) has an oxidation state of +1. Formula: H_xNM.
  • Nomenclature term: hydrogen [non-metal root]-ide.
• Binary Acids (Hydrohalic Acids): Non-metal hydrides (often Group 16 or 17 elements) dissolved in water.
  • Nomenclature term: hydro-[non-metal root]-ic acid.
• Binary Salts: Formed by the reaction of an acid and a metal. Formula: M_xNM_y.
  • Suffix: -ide.

Ternary Compounds

• Hydroxides: Contain the hydroxide ion (OH)^-. Formula: M(OH)_x.
  • Nomenclature: Hydroxide of [Metal Name].
• Oxyacids (Ternary Acids): Formed by the reaction between a non-metal oxide and water. Formula: H_xNM_yO_z.
  • Suffixes depend on the oxidation state of the central non-metal: hypo-...-ous, -ous, -ic, per-...-ic.
• Ternary Salts (Oxyanion Salts): Formed from oxyacids.
  • Acid suffix -ic converts to salt suffix -ate.
  • Acid suffix -ous converts to salt suffix -ite.

Nomenclature Examples

• Metal Oxides:
  • Co₂O₂ → CoO (Cobalt(II) oxide) → Cobaltous oxide.
  • Co₂O₃ (Cobalt(III) oxide) → Cobaltic oxide.
• Non-metal Oxides:
  • C₂O₂ → CO (Carbon monoxide).
  • C₂O₄ → CO₂ (Carbon dioxide).
• Metal Hydride: LiH → Lithium hydride.
• Non-metal Hydride: H₂S → Hydrogen sulfide.
• Special Hydride: NH₃ (Hydrogen nitride) → Ammonia.
• Binary Acid: H₂S → Hydrosulfuric acid.
• Salt Formation (Binary): HCl + Na → NaCl → Sodium chloride.
• Hydroxide: Na(OH) → Sodium hydroxide (Common name: Caustic soda).
• Oxyacid Formation: CO₂ + H₂O → H₂CO₃ → Carbonic acid. (Note: Prefixes Hypo- and Per- are used for varying oxidation states.)
• Salt Formation (Ternary): H₂CO₃ + K → K₂CO₃ → Potassium carbonate.

Foundations of Atomic Theory

Dalton's Atomic Postulates (Early 1800s)

John Dalton proposed several key assumptions regarding the nature of matter:

• Matter is composed of tiny, indivisible particles called atoms.
• Atoms of the same element are identical in mass and properties. Atoms of different elements are different.
• Elements combine in simple, whole-number ratios to form compounds (Law of Multiple Proportions).
• Compounds formed by the union of elements maintain a constant weight ratio (related to the Law of Definite Proportions).

Rutherford's Gold Foil Experiment

Ernest Rutherford's experiment consisted of bombarding a thin sheet of gold foil with positively charged alpha particles. A fluorescent screen was placed around the foil to observe the results.

Observations and Conclusions:

• Most alpha rays passed through the foil undeflected. This indicated that the majority of the space within an atom is empty space.
• Some rays were deflected slightly. This occurred when alpha particles passed very close to electric charge centers of the same type (positive charge).
• Very few rays bounced back. This indicated that the positive charge and mass of the atom are concentrated in a tiny, dense region called the nucleus, causing a head-on collision.