Chapter 7-8 Flashcards
What are the high points of waves?
Crests
What are the low points in a series of waves?
Troughs
What is the distance between any two corresponding points on successive waves?
Wavelength
What is a measurement from the equilibrium to the highest or lowest point of the wave? It is the strength of the wave.
Amplitude
What is the number of complete waves that pass by a point in a given time?
Frequency
What is the SI unit of frequency?
Hertz
Hz)=(1/s
What is the rate at which the wave travels?
Speed
Sir Isaac Newton proposed what, the idea that light can be pictured as streams of tiny particles emitted by light sources?
Particle theory of light
What did Christian Huygens propose which states that light consists of a series of waves rather than individual particles?
Wave theory of light
In the 1860s, the brilliant Scottish physicist James Clerk Maxwell showed that a light wave can be accurately described in terms of an electric field and a magnetic field vibrating at right angles to each other. What are these two vibrating fields act together as?
A single electromagnetic wave
The measured speed of light in a vacuum never varies.
What can be described as a periodic back-and-forth motion that transmits energy?
Wave
What is the speed of light?
3.00 x 10^8 m/s
What is an arrangement of all forms of electromagnetic radiation in order of frequency and wavelength?
Electromagnetic spectrum
What is the two sided nature of light called?
Wave-particle duality
What states that light consists of tiny bundles or “packets” of energy called photons?
The quantum theory of light
The amount of energy a photon contains is proportional to its frequency.
What is a photon?
When interacting with matter, photons act like particles. When traveling through space, photons act as waves.
What is electromagnetic waves traveling as photons?
Light
It must consist of whole numbers of photons; a half photon cannot exist.
According to the quantum theory, the energy of a photon is directly proportional to its frequency. Describe this mathematically.
E = hf
E=energy, f=frequency, h=Planck’s constant (6.63x10^-34 Jxs)
What did scientists know about an atom by the early 1900s?
That it consists of a dense, central core, the nucleus, which is surrounded by smaller, fast-moving electrons.
A more precise instrument called what, can be used in a laboratory to separate the colours further and study them in more detail?
Spectrometer
What is a spectrum containing only certain colours?
Line spectrum
What is a spectrum containing the complete array of colours, by contrast?
Continuous spectrum
The electron in the hydrogen atom can move about the nucleus only in specific orbits called what?
Energy levels
What does “quantized” mean?
Restricted to certain values.
What is the quantum number?
6.63 x 10^-34 Jxs
What is the ground state?
The lowest energy state of the hydrogen atom
What are excited states?
All other higher energy states.
As long as the electron in a hydrogen atom stays within a given energy level, it cannot radiate any energy. Only certain orbits are allowed; the energy of the allowed orbits is quantized, as given by what expression?
E = -J/n^2
The waves de Broglie proposed are not electromagnetic waves but are ________ ________?
Matter waves
They can not move at the speed of light.
The electron can be shown to behave as a wave as well as a particle.
What is the equation for matter waves wavelength?
Wavelength = Planck’s constant (h) / mas (m) x velocity (v)
According to what model, an electron in an atom behaves as a three dimensional matter wave containing an integral number of wavelengths in an orbit?
Wave-mechanical model
What is a three dimensional matter wave containing an integral number of wavelengths in an orbit?
Standing wave
What is Heisenberg’s uncertainty principle?
It is impossible to simultaneously determine the momentum and the position of an electron with precision; either momentum or position may be precisely measured but not both.
What is the difference between an orbital and an orbit?
An orbital is a region of space in which there is a high probability of finding the electron, whereas an orbit (used in the Bohr model) is a definite path in space.