CHEM 201 - Light, Atomic Structure, and Emission Spectra

Flashcards covering concepts from CHEM 201 lecture notes on light as wave and particle, atomic emission spectra, electromagnetic radiation, photon energy, and applications like flame tests and aurora.

What are the two ways light can be considered?

Light can be considered both as a wave and as particles (photons).

What phenomenon provides clues for the electronic structure of an atom?

Atomic Emission (Line) Spectra provide clues for the electronic structure of an atom.

How do atoms emit light in a flame test?

Atoms of certain elements become excited by the heat from a flame, gain energy, and then emit light as they relax.

What is the key difference when white light versus light from excited gaseous atoms is refracted by a prism?

White light produces a continuous spectrum, while light from excited gaseous atoms produces only a few individual lines, called an emission/atomic spectrum.

What is electromagnetic radiation?

Electromagnetic radiation encompasses all forms of light and radiation, consisting of oscillating electric and magnetic fields that are perpendicular to each other.

Define wavelength (
R
) and frequency (
0
) of a wave.

Wavelength (λ) is the distance between two successive peaks of a wave, and frequency (ν) is the number of cycles per second (unit: Hertz, Hz or s-1).

What is the relationship between the speed of light (c), wavelength (
R
), and frequency (
0
)?

The relationship is c = λ × ν, where c is the speed of light (2.998 x 10^8 m/s in vacuum).

Who proposed that light has both wave-like and particle-like properties, and that energy is proportional to its frequency?

Max Planck (1900) proposed fixed amounts (quanta) of energy, and Albert Einstein (1905) further developed the idea of light's particle-like properties with photons.

What is the formula for the energy of a photon?

The energy of a photon (Ephoton) is given by Ephoton = h × ν, where h is Planck's constant (6.626 × 10^-34 Joule·sec/photon) and ν is the frequency.

How does the energy of electromagnetic radiation relate to its wavelength and frequency?

Lower frequencies and longer wavelengths correspond to lower energy radiation, while higher frequencies and shorter wavelengths correspond to higher energy radiation (E = hc/λ).

Describe the basic process of atomic absorption, excitation, and emission.

An atom in its ground state absorbs energy, causing an electron to become excited. The excited electron then relaxes by losing energy and emitting light.

What does a line in an atomic emission spectrum represent?

Each line in an atomic emission spectrum represents the energy of a photon emitted during an electron's relaxation from a higher energy level to a lower one, corresponding to a specific energy gap.

Why is the atomic emission spectrum unique for each element?

The atomic emission spectrum is unique for each element because each element has a unique electron configuration and unique quantized energy levels, leading to distinct energy transitions and emitted photon energies.

How are aurora colors produced?

Aurora colors are produced when energetic particles from the Sun collide with oxygen and nitrogen atoms and molecules in Earth's upper atmosphere, causing them to become excited and emit light (e.g., oxygen emits yellow-green/red, nitrogen emits blue/red-purple).

How are X-rays used for elemental detection in synchrotron facilities?

Very intense X-rays from synchrotron facilities are used to excite core electrons; the subsequent relaxation of electrons from higher levels to fill the core 'hole' emits characteristic X-ray light that can be detected to identify elements like mercury.