Language of Chemistry Lecture Notes

Introduction

• Introduction to language of chemistry: تعلم الكيمياء.
• Covered topics: Atoms, molecules, symbols, valency, equations.
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  • Courses: Physics, Chemistry, Biology, Maths, and Computer coding.

Matter

• Definition: Anything that has mass and occupies space.
• Examples of Matter: Water, chair, pizza, juice, air, smoke, iron nails.
• Non-matter: Emotions, energy (light, heat, chemical, sound).
• Classification of Matter:
  • Pure substances: Elements, compounds.
  • Mixtures: Homogeneous, Heterogeneous.

Elements

• Simplest substances that cannot be broken down further: 118 elements.
• Examples: H (Hydrogen), He (Helium), Li (Lithium), Be (Beryllium).
• Represented using symbols; Periodic Table of Elements.
• Particle Theory of Matter: Matter is made up of tiny particles.
  • River water example: Drop of water —> Water molecules (H2O) —> Atoms (H, O) —> Subatomic particles (Protons, neutrons, electrons).

Atoms, Molecules, and Ions

Atoms

• Smallest particle of an element maintaining its properties.
• Examples: H (Hydrogen), He (Helium), Na (Sodium), Cl (Chlorine), O (Oxygen).
• Represented by symbols (e.g., H for Hydrogen).

Molecules

• Stable particles made of one or more atoms.
• Examples: H2 (Hydrogen molecule), He (Helium atom as stable), Na (Sodium atom), Cl2 (Chlorine molecule), O2 (Oxygen molecule).
• Atomicity: Number of atoms in one molecule of an element.
  • Monoatomic: He, Ne, Ar (Noble gases), metals (Na, Ca, Mg).
  • Diatomic: O2, H2, N2, F2, Cl2, Br2, I2.
  • Triatomic: O3 (Ozone).
  • Tetraatomic: P4 (Phosphorus).
  • Octatomic: S8 (Sulfur).
• Atomicity vs. Valency.

Ions and Radicals

• Charged particles, can be positive (cations) or negative (anions).
• Example: H+ (Hydrogen ion), Cl- (Chloride ion), O2- (Oxide ion), N3- (Nitride ion).
• Polyatomic Ions: OH- (Hydroxide ion), SO4 2- (Sulfate ion), NH4+ (Ammonium ion).

Valency

• Combining capacity of an element with others.
• Examples: H (valency 1), Cl (valency 1), O (valency 2), N (valency 3).
• Criss-Cross method for predicting compounds’ formula.

Chemical Changes and Reactions

Physical vs. Chemical Changes

• Physical Changes: No new substance formed, often reversible.
  • Examples: Melting ice, boiling water.
• Chemical Changes: New substance formed, irreversible.
  • Examples: Cooking food, rusting of iron.

Chemical Reactions

• Definition: Process where new substances are formed with new properties.
  • Example: H2 + O2 → H2O.
• Reactants: Substances on the left side of the reaction arrow.
• Products: Substances on the right side of the reaction arrow.

Writing Chemical Equations

• Convert word equations to chemical equations using symbols, molecular formulae.
  • Example: Hydrogen + Oxygen → Water; H2 + O2 → H2O.
• Balance chemical equations.

Exercises

1. Convert word equations to chemical equations:

   • Word Equation: Sodium + Chlorine → Sodium Chloride
   • Chemical Equation: Na + Cl2 → NaCl

2. Balance chemical equations.

3. Examples:

   • Potassium Hydroxide: KOH
   • Magnesium Hydroxide: Mg(OH)2
   • Cuprous Oxide: Cu2O
   • Cupric Oxide: CuO
   • Sulfur Dioxide: SO2
   • Lead(II) Oxide: PbO
   • Lead(IV) Oxide: PbO2

Summary

• Understanding the language of chemistry through symbols, valencies, atomicities, and equations helps simplify and make the concepts more manageable.
• Study regularly, use discussed tables (symbols, valency, atomicity) for reference.
• Practicing balancing equations and converting word problems to chemical equations is crucial.