Radiation and Spectra

Vocabulary practice flashcards covering Chapter 5: Radiation and Spectra, including light behavior, the electromagnetic spectrum, blackbody radiation, atomic structure, spectral lines, and the Doppler effect.

Wavelength ($\lambda$ )

A measure of the distance between like points on a wave, such as crest to crest, measured in meters ($\text{m}$).

Frequency ($f$)

A count of the number of waves passing a given point in one second, measured in Hertz ($\text{Hz}$)… as wavelength increases, frequency decreases

Speed of Light ($c$)

The physical speed at which all forms of electromagnetic radiation travel through a vacuum, related to frequency and wavelength by $c = f \times \lambda$ (equal to $300,000,000\,\text{m/s}$ or $186,000\,\text{miles/s}$).

Photon

A particle of light that carries energy proportional to its frequency, has no mass, and travels at the speed of light $c$.

How is light a wave and a particle?

When light interacts with light, it acts like a wave

When light interacts with matter, it acts like a particle

Photoelectric Effect

The phenomenon in which light is absorbed by matter in quantized amounts, sending electrons flying out of metal, explained by Albert Einstein in 1905.

Who explained Black Body Radiation?

Max Planck explained BBR by proposing light is emitted from matter in quantized amounts

Who explained photoelectric effect?

Einsteinexplained the photoelectric effect by demonstrating that light can be absorbed in quantized amounts called photons.

Energy formula

($E=\frac{hc}{\lambda}=hf$ Where E is energy, h is Planck's constant, c is the speed of light, and ( \lambda ) is wavelength. )

Electromagnetic Spectrum

The entire range of all possible wave frequencies and wavelengths of electromagnetic radiation.

Radio Waves

have the longest wavelength, lowest frequency, & least energy

X Rays & Gamma Rays

have the shortest wavelength, highest frequency, & highest energy

Heat

A form of energy associated with the random motion of atoms or molecules that compose an object.

Temperature

A measure of the average speed of the atoms or molecules in an object or gas resulting from thermal energy.

Absolute Zero

The theoretical temperature at which there is no heat energy and all atomic motion stops, defined as $0\,\text{K}$ ($-273^\circ\text{C}$ or $-460^\circ\text{F}$).

Kelvin Scale

The absolute temperature scale used by astronomers where water freezes at $273\,\text{K}$ and boils at $373\,\text{K}$.

Blackbody Radiation

Electromagnetic radiation emitted by dense objects with temperatures above absolute zero due to the thermal movement and collision of their atoms.

Continuous Spectrum

A continuous rainbow of colors without dark or bright lines, produced by a hot, high-density energy source.

Emission Spectrum

A pattern of bright individual spectral lines emitted by a hot, low-density gas cloud.

Absorption Spectrum

A continuous spectrum containing dark lines caused by a cool, low-density gas cloud absorbing specific wavelengths of light from a hot continuous source.

Spectral curves

Known as black body curves, tell us about a star’s temperature

Spectral lines

absorption/emission lines that tell us what atoms a star contains

Nucleus

The massive, positively charged central region of an atom consisting of protons and neutrons.

Proton

A positively charged subatomic particle located in the nucleus of an atom, whose count determines the chemical element.

Neutron

An uncharged subatomic particle present inside the atomic nucleus alongside protons for stability.

Isotope

Forms of a chemical element containing the same number of protons but a different number of neutrons in their nuclei.

Ion

An atom that has gained or lost one or more electrons, giving it a net positive or negative electrical charge.

Bohr Model

A simplified model of the atom in which electrons move around the nucleus only at specific, allowed discrete energy levels.

Ground State

The lowest permitted energy state for an electron in an atom.

Excited Atom

An atom containing an electron that has absorbed energy and jumped to a higher energy level above its ground state.

Doppler Effect

The apparent shift in the frequency and wavelength of a wave caused by relative motion between the source emitting the wave and the observer.

Redshift

A Doppler shift of spectral lines toward longer wavelengths, indicating that the radiation source is moving away from the observer.

Blueshift

A Doppler shift of spectral lines toward shorter wavelengths, indicating that the radiation source is moving toward the observer.