Dr Adetoro CHM 101 2425

Course Overview

• Course Code: CHM 101

• Course Title: General Chemistry I

• Session: 2024/2025

• Instructor: Dr. R.O. Adetoro

• Department: Pure and Applied Chemistry

• Faculty: Basic and Applied Sciences

Course Synopsis

• Topics Covered:

  • Modern electronic theory of atoms

  • Electronic configuration

  • Periodicity and building up of the periodic table

Historical Models of the Atom

• John Dalton (1803):

  • Atoms as hard, indivisible particles with distinct masses.

• J.J. Thomson (1890s):

  • Discovered charge-to-mass ratio of electrons; atoms are divisible.

• Ernest Rutherford (1910):

  • Discovered the atomic nucleus by experimenting with alpha particles.

• James Maxwell (1873):

  • Proposed visible light consists of electromagnetic waves.

Electromagnetic Radiation

• Definition: Energy transmitted through space as electromagnetic radiation.

• Speed of Light (c): 2.998 × 10^8 m/s.

• Types of Electromagnetic Radiation: X-rays, microwaves, radio waves, etc.

Electromagnetic Spectrum

• Characteristics:

  • Wavelength and frequency determine type of radiation.

  • Visible light is a small part of the spectrum (approx. 400-700 nm).

  • Higher energy forms (e.g., UV) have shorter wavelengths compared to visible light.

Relationship of Wavelength and Frequency

• Wavelength (λ): Distance between peaks of a wave.

• Frequency (ν): Number of waves passing a point per second.

• Energy Relation:

  • As wavelength increases, energy decreases, and vice versa (E = hc/λ).

Electron Configurations and Periodicity

• Aufbau Principle:

  • Electrons fill orbitals from lowest to highest energy.

• Ground State vs. Excited State:

  • Lowest energy configuration is the ground state.

• Order of Filling: 1s, 2s, 2p, 3s, 3p, 4s, etc.

• Valence Electrons: Electrons in the outermost shell involved in chemical reactions.

Periodic Properties

• Periodic Law: Physical and chemical properties vary periodically with atomic number.

• Key Properties to Study:

  • Atomic radius

  • Ionization energy

  • Electron affinity

Atomic Radius

• Decreases across a period and increases down a group.

Ionization Energy

• Energy required to remove an outermost electron.

• Increases across a period and decreases down a group.

Electron Affinity

• Energy change when an electron is added to a neutral atom.

• Trends: More negative electron affinities as you move across a period.