Exam 4 - Light and Electromagnetic Radiation Flashcards
What kind of radiation light is?
Electromagnetic
What are other types of electromagnetic radiation?
X-rays, UV radiation, infrared radiation, etc.
They are all different in qualitative terms and wavelength.
False. Despite having similar qualitative terms, they are all different in wavelengths.
Frequency and wavelength have a direct relationship.
True
Why do different types of EM radiation have different properties?
Because they have different frequencies and wavelengths
What are the main descriptors we use to describe waves?
Wavelength, frequency, amplitude, and velocity
What is the unit for frequency?
Hz (or s-1)
Light behaves like a…
wave
What are some of the wave properties that are particle like instead of wave like?
Blackbody radiation, photoelectric effect, emission spectra
Blackbody radiation
As an object is heated it gives off EM radiation. It is the phenomenon that explains light being given off by a hot object.
The Photoelectric Effect
Electrons are given off when certain substances are struck by light (solar powered objects). There is a minimum amount of energy that has to hit the surface for an electron to be ejected.
Emission spectra
When the electrons of a gas are excited, the gas gives off certain wavelenghts of light
A light particle is
A photon
The amount of energy contained in a photon is…
Quantum
What is the Line Spectra?
The depiction of different wavelengths of light given off by different elements. . A spectrum consisting of only a few discrete wavelengths of light is called a line spectrum. Ex: Line spectra for sodium and hydrogen
When the energy is lowest, n =1. This is referred to as…
The ground state. The other states are referred to as excited states
When is radiation given off?
When an electron leaves a higher level to a lower level.
When is radiation acquired?
When an electron leaves from a lower level to a higher level.
According to the Bohr model, as the energy goes up, the difference between energy levels gets smaller
True
What is the visible light spectrum?
From 380 - 700 nm
What does DeBroglie wavelengths suggest?
That every moving matter has a wavelength, even though the real world objects are too small to be observed or have any practical meaning
What is the Uncertainty Principle?
It states that we cannot know exactly the location and momentum of an electron at the same time.
The more precisely we know position, the less precise our knowledge of momentum.
True
The Uncertainty Principle has no effect on electrons.
False. The uncertainty principle has no effect in the real world but it is highly significant for electrons
What is the wavelenght?
The space between peaks of successive points. Abbreviated for lenda
What is amplitude?
Spatial distance of wave from baseline (it describes intensity or how loud a certain sound is)
What is frequency?
How many wave peaks occur in a given amount of time. Abbreviation is Hz, which means per second
What is amplitude?
The height of a wave, from baseline to peak
What is the velocity of EM waves?
3.0x10^8 m/s (speed of light)
10^-10
Angstrom (x-ray)
10^-9
Nanometers (ultraviolet, visible)
10^-6
Micrometers (infrared)
10^-3
Milimeters (infrared)
10^-2
Centimeters (microwave)
1
meters (TV, radio)
Quantized energy
The particle nature of light was first proposed by Max Planck in his explanation of blackbody radiation.
-Planck stated that energy can only be released or absorbed in discrete chunks of some minimum size. He called these chunks of energy “quantum”. One quantum is the smallest amount of energy that can be absorbed or released. The amount of energy of a quantum of light depends on its frequency.
E = hν
What is the binding energy?
The amount of energy necessary to kick off an electron.
What happens if the biding energy is greater than the energy of the photon? And what happens if it is smaller than the energy of the photon?
If it is greater than no electrons are ejected; if it is smaller than an electron is ejected.
What is the difference between the binding energy and the photon energy?
It is the electron’s kinetic energy representede by KE = hv - binding energy; also referred to as work function
What is a spectrum?
The set of wavelengths given off or absorbed by a material. It can be continuous or it can be a line spectrum
What is a continuous spectrum?
A continuous spectrum contains all the wavelengths over the wavelength range being studied. An example is the spectrum of white light, which contains all visible colors
As the energy level goes up, the difference between energy levels gets smaller
True
The more precisely we know position…
The less precisely we know location
Because of the uncertainty principle we cannot speak of an electron’s position…
Only about the probability that it will be in a certain position.
Which of these bands of the electromagnetic spectrum is highest in energy?
X-ray
An electron drops from a higher energy orbital to a lower energy orbital. This is generally accompanied by ______________.
Emission of electromagnetic radiation
