Chemistry Final Exam Flashcards
What are examples of electromagnetic radiation
Visible light, x- rays, radio waves, & microwaves
What are the properties of the wave nature of light?
- Frequency (v)
- Wavelength (lambda)
- Speed ( meters)
- Amplitude ( height of the crest of a wave)
electromagnetic spectrum:
a continuum of wavelengths of radiant energy
From lowest to highest frequency, what order are the different areas of the electromagnetic spectrum
Gamma ray, X-ray, Ultraviolet, Visible light, infrared, Microwave, Radio waves
Refraction definition
The phenomenon in which a wave changes its speed and therefore its direction as it passes through a phase boundary to a different medium
`Dispersion definition
the phenomenon in which a wave striking the edge of an object bends around it. A wave passing through a slit as wide as its wavelength forms a circular wave
Interference definition:
Constructive and destructive; constructive: amplitudes add together to form a brighter region, destructive: amplitudes cancel to form a darker region`
Blackbody radiation
When a solid is heated to about 1000K, it begins to emit visible light
Particle nature of light
- Blackbody radiation
2. quantum theory E= nhv
Planck’s constant:
6.626 x 10^-34 (J)(s)
Quantum
A packet of energy equal to hv. The smallest quantity of energy that can be emitted or absorbed
Photoelectric effect and the Photon theory of light
When monochromatic light of sufficient frequency shines on a metal plate, a current is produced
Threshold frequency
For current to flow, the light shining on the metal must have a minimum or threshold frequency
Absence of time lag:
Current flows the moment light of the minimum frequency shines on the metal regardless of the light’s intensity
Photon theory
Ephoton = hv = deltaEatom
Line spectrum definition
a series of fine lines at specific frequencies separated by black spaces
Rydberg equation
1/lambda = R((1/n1^2)-(1/n2^2)
Postulates of the Bohr model
- The H atom has only certain energy levels which Bohr called stationary states. Each state is associated with a fixed circular orbit around the nucleus. The higher the energy level, the farther it is from the nucleus
- The atom does NOT radiate energy while in one of its stationary states
- The atom changes to another stationary state (the electron moves to another orbit) only by emitting or absorbing a photon. The energy of the photon equals the energy of the two states
Features of the Bohr’s model
- Quantum numbers and electron orbit (n is a positive integer)
- Ground state
- Excited States
- Absorption
- Emission
Ground State definition
When the electron is in the 1st orbit (n=1), it is closest to the nucleus and the H atom is in its lowest energy level
Excited states definition
Any other orbit than the ground state
Absorption
If an atom absorbs a photon whose energy equals the difference between lower and higher energy levels, the electron moves to a higher energy orbit
Emission definition
If an H atom in a higher energy level (electron in a farther orbit) returns to a lower energy level (electron in a closer orbit), the atom emits a photon whose energy equals the difference between the two levels
How the model explains line spectra
Since an atom’s energy is not continuous, but rather has only certain states, an atomic spectrum is not continuous
