Chapter 2 (2.1): Atomic Theory and Electromagnetic Radiation

Vocabulary flashcards covering key concepts from the lecture notes on Atomic Theory and Electromagnetic Radiation.

Solid Sphere Model

Early atomic model portraying atoms as solid, indivisible spheres with no internal structure.

Plum Pudding Model

Thomson’s model: atom as a positively charged ‘pudding’ with embedded electrons; no nucleus.

Nuclear Model

Rutherford’s model: atom mostly empty space with a tiny, dense, positively charged nucleus at the center.

Planetary Model

Bohr’s refinement: electrons travel in fixed circular orbits around the nucleus with quantized energies.

Quantum Model

Schrödinger’s model: electrons exist in orbitals (probability clouds) with quantized energy levels.

Dalton’s Atomic Theory

Atoms are indivisible; atoms of the same element are identical; compounds form by combining atoms.

Electron (corpuscle)

Negatively charged subatomic particle discovered by Thomson; component of atoms.

Nucleus

Center of the atom containing protons (and later neutrons); positive charge; very small.

Energy Levels

Discrete energies that electrons can occupy; transitions involve photon emission or absorption.

Orbital

Region in space where there is a high probability of finding an electron; described by quantum numbers.

Planck’s Constant (h)

Constant relating energy and frequency: E = hν; h ≈ 6.626 × 10^-34 J·s.

Photon

Quantum of light energy; exhibits particle-like and wave-like properties; energy E = hν.

Wavelength (λ)

Distance between successive crests of a wave; measured in meters; inversely related to frequency.

Frequency (ν)

Number of cycles per second; unit s^-1 (Hz); proportional to photon energy via E = hν.

Speed of Light (c)

Constant in vacuum, c ≈ 3.0 × 10^8 m/s; relates wavelength and frequency by c = λν.

Electromagnetic Spectrum

All electromagnetic radiation ordered by wavelength or frequency (gamma to radio).

Balmer Series

Hydrogen emission lines in the visible region from transitions to n = 2.

Emission Spectrum

Bright lines produced when atoms emit photons; lines are characteristic of each element.

White Light

Light composed of a continuum of wavelengths across the visible spectrum.

Absorption

Process where a system gains energy by absorbing a photon.

Emission

Process where a system loses energy by emitting a photon.

E = hν

Photon energy equals Planck’s constant times frequency.

E = hc/λ

Photon energy expressed via wavelength (alternative form of photon energy).

Visible Spectrum Range

Approximate wavelength range of visible light: ~400–750 nm.