Atomic Models and Subatomic Particles

Atomic Models

• Dalton's Model: Proposed the atom as indivisible and indestructible. Matter consists of atoms; different elements have different atoms.
• Thomson's Model (Plum Pudding Model): Suggested that atoms are composed of electrons (negative charges) scattered within a positively charged 'soup'.
• Rutherford's Model: Introduced the nucleus, showing atoms have a small, dense positive center (nucleus) with electrons orbiting around it.
• Bohr Model: Built on Rutherford’s model; proposed that electrons move in fixed orbits at specific distances from the nucleus, with quantized energy levels.
• Quantum Mechanical Model: Describes the behavior of electrons in probabilistic terms; electrons occupy clouds (orbitals) rather than fixed paths.

Subatomic Particles

• Protons:
  • Positive charge (+1)
  • Located in the nucleus
  • Determines atomic number and identity of the element
• Neutrons:
  • No charge (neutral)
  • Located in the nucleus
  • Contributes to atomic mass and stability of the nucleus
• Electrons:
  • Negative charge (-1)
  • Orbit around the nucleus in energy levels
  • Involved in chemical bonding and reactions

Electron Configurations

• Describes the arrangement of electrons in an atom.
• Follows the Aufbau principle (electrons fill lowest energy orbitals first).
• Follows Pauli Exclusion Principle (no two electrons in an atom can have the same set of four quantum numbers).
• Follows Hund’s Rule (electrons will fill degenerate orbitals singly before pairing up).
• General Configuration Notation:
  • Electron configurations are written in the format of subshells: e.g., 1s² 2s² 2p⁶ (for Neon).
• Valence electrons are important for determining chemical reactivity.

Isotopes And Ions

• Isotopes:
  • Atoms of the same element with the same number of protons but different numbers of neutrons.
  • Examples: Carbon-12, Carbon-14 (both have 6 protons but different neutrons).
  • Impact on atomic mass and nuclear stability.
• Ions:
  • Charged atoms formed by the loss or gain of electrons.
  • Cations: Positively charged ions (loss of electrons).
    • Example: Na⁺ (sodium ion).
  • Anions: Negatively charged ions (gain of electrons).
    • Example: Cl⁻ (chloride ion).
• Ions play crucial roles in chemical bonding and electrical conductivity.

Atomic Models

• Dalton's Model proposed that atoms were indivisible and indestructible.
• Thomson's Model, also known as the "Plum Pudding Model", suggested that atoms were composed of negatively charged electrons scattered within a positively charged "soup".
• Rutherford's Model introduced the concept of the nucleus, showing atoms have a small, dense, positively charged center with electrons orbiting around it.
• Bohr Model built upon Rutherford's model and proposed that electrons move in fixed orbits at specific distances from the nucleus, with quantized energy levels.
• Quantum Mechanical Model describes electrons in probabilistic terms, existing within clouds (orbitals) rather than fixed paths.

Subatomic Particles

• Protons are located in the nucleus and carry a positive charge. They determine the atomic number and therefore the identity of an element.
• Neutrons are also located in the nucleus and carry no charge. They contribute to the atomic mass and stability of the nucleus.
• Electrons carry a negative charge, orbit the nucleus in energy levels, and are responsible for chemical bonds and reactions.

Electron Configurations

• Electron configurations describe the arrangement of electrons within an atom.
• Electrons fill orbitals according to the Aufbau principle, filling the lowest energy orbitals first.
• The Pauli Exclusion Principle states that no two electrons in an atom can have the same set of four quantum numbers.
• Hund's Rule dictates that electrons will fill degenerate orbitals singly before pairing up.
• General Configuration Notation uses subshells to express electron configurations, like 1s² 2s² 2p⁶ for Neon.
• Valence electrons are the electrons in the outermost shell and are crucial in determining chemical reactivity.

Isotopes And Ions

• Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons.
• Isotopes affect atomic mass and nuclear stability. For example, Carbon-12 and Carbon-14 both have 6 protons but different numbers of neutrons.
• Ions are charged atoms formed by the loss or gain of electrons.
• Cations are positively charged ions formed by the loss of electrons. For example, Na⁺ (sodium ion).
• Anions are negatively charged ions formed by the gain of electrons. For example, Cl⁻ (chloride ion).
• Ions are essential for chemical bonding and electrical conductivity.