CHE 1001 CHA. 1 INTRODUCTION (BASIC TOOLS OF CHEMISTRY)

1.1 PROPERTIES OF MATTER

  • Definition of Matter: Anything that occupies space and has mass.

  • Composition: Parts of a sample and their proportions (e.g., water = 11.19% H, 88.81% O).

1.2 CLASSIFICATION OF MATTER

Substances

  • Substance: Matter with a definite composition (e.g., water, gold).

  • Properties: Distinct characteristics used to identify substances.

Mixtures

  • Mixture: Combination of two or more substances retaining identities (e.g., air, seawater).

  • Homogeneous mixtures have uniform composition (e.g., sugar in water).

  • Heterogeneous mixtures have non-uniform composition (e.g., sand and iron filings).

1.3 MEASUREMENT OF MATTER

SI Units

  • Base Quantities: Length (m), Mass (kg), Time (s), Temperature (K).

  • Derived Units: Other quantities (e.g., density = mass/volume).

Mass and Weight

  • Mass: Quantity of matter (kg, g).

  • Weight: Force of gravity on an object.

1.4 UNCERTAINTIES IN SCIENTIFIC MEASUREMENTS

Accuracy vs. Precision

  • Accuracy: Closeness to actual value.

  • Precision: Closeness of repeated measurements.

1.5 SIGNIFICANT FIGURES

  • Counting Rules: Non-zero digits count. Leading zeros don’t, captive zeros do, trailing zeros count if decimal is present.

1.6 DIMENSIONAL ANALYSIS

  • Conversion Method: Using conversion factors to change units.

1.7 THE MOLE CONCEPT

  • Mole: Amount that contains Avogadro's number (6.022 x 10²³) of particles.

  • Molar Mass: Mass in grams of one mole of a substance (e.g., H2O = 18.02 g/mol).

1.8 CHEMICAL COMPOUNDS

Bonding Types

  • Covalent bonds: Sharing of electrons (molecular compounds).

  • Ionic bonds: Transfer of electrons (ionic compounds).

Compound Formulas

  • Empirical Formulas: Simplest ratio of elements.

  • Molecular Formulas: Actual numbers of atoms in a molecule.

1.7 THE MOLE CONCEPT

  • Mole: The mole is a fundamental unit in chemistry that represents a specific number of particles (atoms, molecules, ions, etc.). One mole of any substance contains Avogadro's number, which is approximately 6.022 x 10²³ particles.

  • Importance of the Mole: The mole allows chemists to convert between the microscopic world of atoms and molecules and the macroscopic world of grams and liters. It serves as a bridge to relate the quantities of reactants and products in chemical reactions.

  • Molar Mass: The molar mass is the mass of one mole of a substance typically expressed in grams per mole (g/mol). It reflects the mass of individual molecules or formula units and is calculated by summing the atomic masses of the elements in the compound. For example, the molar mass of water (H2O) is approximately 18.02 g/mol (2 x 1.01 g/mol for hydrogen + 16.00 g/mol for oxygen).

  • Calculating Moles: To find the number of moles of a substance, you can use the formula:

    [ \text{Number of Moles} = \frac{\text{Mass (g){\text{Molar Mass (g/mol) ]

  • Applications of the Mole Concept: The mole concept is essential for stoichiometry in chemical reactions, enabling chemists to predict yields, determine reactant needs, and analyze reaction outcomes.