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General Chemistry: Atomic Theory, Energy, and Quantum Mechanics

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Termini in questo insieme (27)

  • Law of Conservation of Mass

    Matter is neither created nor destroyed in a chemical reaction.

  • Law of Multiple Proportions

    When two elements form different compounds, the masses of one element that combine with 1 g of the other are in ratios of small whole numbers.

  • Dalton's Atomic Theory - Key Points

    1. Elements are made of indestructible atoms.
    2. Atoms of an element are identical.
    3. Atoms combine in whole number ratios.
    4. Atoms cannot change into other elements.

  • Isotopes and Dalton's Theory

    Isotopes contradict Dalton's idea that all atoms of an element are identical because they have different numbers of neutrons.

  • Endothermic vs Exothermic Processes

    Endothermic: system gains energy.
    Exothermic: system loses energy.

  • Phase Changes: Endothermic Examples

    Fusion (s → l), Vaporization (l → g), Sublimation (s → g) are endothermic phase changes.

  • Phase Changes: Exothermic Examples

    Freezing (l → s), Condensation (g → l), Deposition (g → s) are exothermic phase changes.

  • Precision vs Accuracy

    Precision: consistency of measurements.
    Accuracy: closeness to the true value.

  • Kelvin Temperature Scale

    Kelvin (K) is an absolute temperature scale starting at 0 K; conversion: \(K=C+273.15\).

  • Density Formula

    Density (d) = mass (m) / volume (v); density is an intensive property.

  • Pure Substance vs Mixture

    Pure substance: one component with fixed composition.
    Mixture: two or more components varying in composition.

  • Subatomic Particles and Their Charges

    Protons (+), Neutrons (0), Electrons (-).

  • Rutherford's Nuclear Model

    Atom has a small, dense, positively charged nucleus; most of the atom is empty space with electrons dispersed.

  • Neutron Discovery and Role

    Neutrons have no charge, slightly heavier than protons, and shield protons from repelling each other in the nucleus.

  • Atomic Number (Z)

    Number of protons in an atom; defines the element.

  • Mole Concept

    1 mole = 6.022 x 1023 particles; number of atoms in 12 g of carbon-12.

  • Isotopes

    Atoms of the same element with different numbers of neutrons but the same number of protons.

  • Ions: Cations and Anions

    Cations: positively charged, lost electrons.
    Anions: negatively charged, gained electrons.

  • Wave Properties: Frequency and Wavelength

    Frequency (v) and wavelength (λ) are inversely proportional: \(v \times \lambda = c\), where c is speed of light.

  • Photoelectric Effect

    Electrons are ejected from a metal only if light has a frequency above a threshold; explained by photons with energy \(E=hv\).

  • Bohr Model of the Atom

    Electrons orbit nucleus in fixed energy levels; emit photons when jumping to lower energy orbits.

  • Heisenberg's Uncertainty Principle

    It is impossible to know both the exact position and momentum of an electron simultaneously.

  • Principal Quantum Number (n)

    Indicates the energy level of an electron; n ≥ 1; higher n means higher energy and larger orbitals.

  • Angular Momentum Quantum Number (l)

    Determines orbital shape; values from 0 to n-1; s (0), p (1), d (2), f (3) orbitals.

  • Magnetic Quantum Number (ml)

    Specifies orbital orientation; values from -l to +l including zero.

  • Electron Spin Quantum Number (ms)

    Electron spin can be +1/2 (spin up) or -1/2 (spin down); two electrons in an orbital must have opposite spins.

  • Pauli Exclusion Principle

    No two electrons in an atom can have the same set of four quantum numbers (n, l, ml, ms).