Glossary
Absorption (of photons)
The process where an atom gains energy by taking in a photon, causing an electron to jump to a higher energy level.
Example:
A plant performs photosynthesis by the absorption of sunlight photons by chlorophyll molecules.
Absorption Spectrum
A unique pattern of dark lines at specific wavelengths produced when a continuous spectrum of light passes through a gas, and atoms absorb photons corresponding to their energy transitions.
Example:
The dark lines in the Sun's absorption spectrum reveal the presence of elements like hydrogen and helium in its outer atmosphere.
Atomic Model
A conceptual representation of an atom, typically depicting a nucleus and electrons occupying specific energy levels.
Example:
The Bohr atomic model helped explain why hydrogen atoms emit light at specific wavelengths.
Atomic Transitions
The movement of an electron between different quantized energy levels within an atom, involving the absorption or emission of a photon.
Example:
When an electron in a sodium lamp moves from a higher to a lower atomic transition state, it emits a yellow photon.
Binding Energy
The minimum amount of energy needed to completely remove an electron from an atom, overcoming the electrostatic attraction to the nucleus.
Example:
The binding energy of an electron in the ground state of a hydrogen atom is 13.6 eV.
Emission (of photons)
The process where an atom loses energy by releasing a photon, as an electron drops to a lower energy level.
Example:
A neon sign glows due to the emission of photons by excited neon atoms returning to lower energy states.
Emission Spectrum
A unique pattern of bright lines at specific wavelengths produced when excited atoms of an element emit photons as their electrons return to lower energy states.
Example:
Astronomers use the emission spectrum of distant stars to determine their elemental composition.
Energy Level Diagrams
Diagrams that visually represent the quantized energy states of an atom and illustrate possible electron transitions between these states.
Example:
An energy level diagram for hydrogen clearly shows the transitions that produce the Balmer series lines in its spectrum.
Energy Levels
Specific, quantized amounts of energy that an electron can possess within an atom.
Example:
An electron in a hydrogen atom can only exist at discrete energy levels, not in between them.
Excited States
Any energy level higher than the ground state that an electron can occupy after absorbing energy.
Example:
When an atom absorbs a photon, its electron jumps from the ground state to an excited state.
Frequency (f)
The number of wave cycles (or photon oscillations) that pass a point per unit of time, related to photon energy.
Example:
Radio waves have a much lower frequency than X-rays, meaning they carry less energy per photon.
Ground State
The lowest possible energy level that an electron can occupy within an atom.
Example:
An atom is most stable when its electrons are in the ground state.
Ionization
The process by which an atom gains or loses electrons, resulting in a net electrical charge and forming an ion.
Example:
If a high-energy photon strikes an atom and removes an electron, ionization occurs, creating a positive ion.
Photon Energy
The energy carried by a single photon, directly proportional to its frequency and inversely proportional to its wavelength.
Example:
A blue light photon energy is higher than a red light photon energy because blue light has a shorter wavelength.
Photons
Discrete packets of light energy that mediate energy transfer at the atomic level.
Example:
When a light bulb glows, it emits countless photons that carry light energy to your eyes.
Planck's Constant (h)
A fundamental physical constant that relates the energy of a photon to its frequency ($E=hf$).
Example:
Planck's constant is essential for calculating the energy of individual light quanta.
Speed of Light (c)
The constant speed at which all electromagnetic radiation, including photons, travels in a vacuum.
Example:
The speed of light is a universal constant, approximately m/s, used in many physics calculations.
Wavelength (λ)
The spatial period of a wave, or the distance over which the wave's shape repeats, inversely related to photon energy.
Example:
Red light has a longer wavelength than violet light, which is why it appears at the opposite end of the visible spectrum.