Rutherford's Atomic Theory Quiz

Atomic Structure

• Atoms of different elements have unique characteristics due to their distinct atomic structures, which are determined by the number of protons and electrons.

Dalton's Atomic Theory

• Proposed by John Dalton in the 18th century
• Postulates:
  • Matter is composed of atoms, which are indivisible and indestructible
  • All atoms of an element are identical, but different elements have different atoms
  • Chemical reactions involve the rearrangement of atoms
  • Atoms cannot be created or destroyed, only transformed
• Successfully explained laws of chemical reactions, including the Law of Conservation of Mass and the Law of Definite Proportions
• Limitations: unable to explain the existence of isotopes and the structure of atoms

Thomson Atomic Model

• Proposed by J.J. Thomson in the early 1900s
• Describes the atomic structure based on the cathode ray experiment
• Discovery of electrons, which are negatively charged subatomic particles

Rutherford Atomic Theory

• Proposed by Ernest Rutherford, a student of Thomson
• Modified the atomic structure with the discovery of the nucleus
• Atomic model based on the alpha ray scattering experiment
• Nucleus is at the center of the atom, with electrons orbiting around it in circular paths
• Limitations: unable to explain the stability of atoms and the line spectrum observed

Atomic Structure - Rutherford's Model

• Nucleus is at the center of the atom, where most of the charge and mass is concentrated
• Electrons revolve around the nucleus in circular orbits
• Protons and neutrons make up the nucleus
• Electrons are negatively charged and much lighter than protons and neutrons

Subatomic Particles

• Protons:
  • Positively charged
  • Charge: 1e (approximately 1.602 × 10^-19)
  • Mass: approximately 1.672 × 10^-24
• Neutrons:
  • Electrically neutral
  • Mass: approximately 1.674 × 10^-24
• Electrons:
  • Negatively charged
  • Charge: -1e (approximately -1.602 × 10^-19)
  • Mass: approximately 9.1 × 10^-31

Isotopes

• Variants of an element with the same atomic number but different mass numbers
• Differ in the number of neutrons in their nuclei
• Examples: protium, deuterium, and tritium (isotopes of hydrogen)

Bohr's Atomic Theory

• Proposed by Niels Bohr in 1915
• Postulates:
  • Electrons occupy discrete orbits (stationery orbits) around the nucleus
  • Energy levels of these shells can be represented by quantum numbers
  • Electrons can jump to higher energy levels by absorbing energy and move to lower energy levels by emitting energy
• Limitations: unable to explain the spectra of multi-electron species and the Stark and Zeeman effects

Quantum Mechanics

• Heisenberg's uncertainty principle: no two conjugate physical quantities can be measured simultaneously with 100% accuracy
• Pauli's exclusion principle: no two electrons can have the same set of four quantum numbers
• Hund's rule of maximum multiplicity: degenerate orbitals must be singly filled first, then paired

Electronic Configuration

• The distribution of electrons in atomic orbitals
• Determines the valency of an element and can be used to predict the properties of a group of elements
• Examples: electron configuration of sodium is 1s2 2s2 2p6 3s1