Chem- 5.3 Waves & Electromagnetic Spectrum

What is the relationship (the equation) between frequency and wavelength?

Frequency and wavelength have an inversely proportional relationship. c = λ v Where c is the speed of light and is 3.0 x 10^8 m/s

What is the ground state of an electron and what is the excited state of an electron?

Ground state - e- is in its lowest energy position; stable. Excited state - e- has moved to a higher energy position; unstable

What is the relationship between frequency and energy?

As frequency increases, energy increases.

What is a photon and how do you calculate its energy?

A photon is a tiny packet of light energy. It turns out the energy of the photon is E(photon) = hv where h is Planck's constant.

What is the proof for light as a particle?

Black body experiment Photoelectric effect Hydrogen line emission spectra

What is the proof for light as a wave?

Diffraction experiments have long shown that light is a wave. Sunlight separates into a continuous spectrum when passed through a prism. This is classical physics.

How are the two equations (Energy of a quanta and speed of light) related?

E(quanta)= hv where h is Plank's constant and equal to 6.626 x 10^-34 Js c = λ v where c is the speed of light and equal to 3.0 x 10^8 m/s therefore, E(quanta)= h(c/λ) So just as every lightwave has its own wavelength, frequency and energy, so does every quanta.

What is the Photoelectric effect?

Einstein used Planck's quantum theory to explain the Photoelectric Effect. He said each quanta of light striking the surface of the metal behaves as a tiny particle he called photon. If the energy of the photon is sufficiently large enough, an e- will be released from the surface of the metal.

Is light a wave or a stream of particles (called photons)?

IT IS BOTH!!!! Light travels through space as waves, but interacts with matter as particles. On a macroscopic scale light behaves as a wave. It obeys the laws of classical physics. But on an atomic scale, light behaves as a particle. It obeys the laws of Quantum Mechanical physics.

How does Quantum Mechanics differ from Classical Mechanics?

In brief, the main difference between quantum and classical physics is the difference between a ramp and a staircase Classical physics- saw light as only continuous Quantum Mechanics- saw light as discontinuous (but also saw it as particles and waves)

What did Bohr's statements reveal and his new model of the Atom?

It introduced Quantum Mechanics!!!

What is the Black body experiment? Also, what is Planck's constant?

Maxwell Planck Planck explained the Blackbody experiment as such: He concluded that light is emitted and absorbed by atoms in small quantities he called quanta. Quanta (pl.) or Quantum (s.) We say energy is "quantized". E(quanta)= hv Planck's constant (h) = 6.626 x 10^-34 Js Much like a wave, the energy of a quanta is proportional to the frequency and inversely proportional to the wavelength. The difference is that matter absorbs these quanta only as whole separate packets.

What is the hydrogen line emission spectrum (experiment)?

Niels Bohr (1913) When light being emitted from atoms (think of flame test, spectral tubes) is passed through a prism, it does NOT create a continuous spectrum like that of sunlight. Instead, only a few select lines of color appear. Bohr also used Planck's quanta to explain the line emission spectra. He said electrons, like waves, have wavelengths (he was right) and that the only orbits it could be in were those that had room for a whole number of wavelengths. For example, if the wavelength of an electron were 2 nm, it could only fit in orbits that were 2 nm, 4 nm, 6 nm, etc., in circumference, but not in an orbit with a circumference of, say, 3 nm. Therefore atoms have only certain fixed ("quantized") E-levels and nothing in between. So if Planck discovered the puzzle piece (the quantum), Bohr discovered how it fits an atom (the energy levels). E(energy level) = (n) hv where n is a whole number 1, 2, 3, ...

What are the Paschen, Balmer, and Lyman Series?

Paschen- (Series III)- infrared light Balmer- (Series II)- visible light Lyman- (Series I)- ultraviolet light

What are three objects that separate light?

Prisms, Spectroscope, and Spectral Paper

Just explain a little bit: proof of light as continuous wave and proof of light as streamed particles.

Sunlight is a continuous spectrum. There is no separation between the wavelengths (hence frequencies) of light. This is proof that light is a continuous wave. Elements, such as the mercury in this bulb, separate into discrete (separate) lines. Only the frequencies associated with these wavelengths enter the atom. Thus light is absorbed by atoms in packets of specific energy. This is proof that light is a particle.

What is the speed that all waves travel at?

The speed of light c= 3.0 x 10^8 m/s

In the electromagnetic spectrum, where does visible light fall?

Visible light falls somewhere in the middle and has a range of about 400-800 nm.

What are the two properties of a wave?

Waves have wavelength (λ - the distance between 2 corresponding points on a wave) and frequency (v - the number of waves that pass a fixed point in 1 second. measured in Hertz: Hz, 1/s)

Explain Quantized Energy Levels in Atoms.

Well, Bohr's theory of the structure of an atom is much like the stair analogy: An electron has the exact right amount of energy required to reside on one energy level at a time. It can move up or down to other energy levels. Absorption of energy results in an upward move; down moves release that energy.

Know line spectrum vs. continuous spectrum

You got it!

Electromagnetic Radiation

a type of energy; light energy that radiates through space

how do you convert from nanometers to meters and vice versa?

nm---> m: well, remember that 1 nm is one billionth (10^-9) of a meter so for example if you are given 2 nm to convert to meters, just write out: 2 x 10^-9 m---> nm: remember that 1 m contains 1 billion nanometers. so for example if you are given 2 m to convert to nm, just write: 2 x 10^9

Electromagnetic spectrum

the range of all forms of electromagnetic radiation from radio to gamma waves.

How do you calculate the amount of energy in an electron transition?

ΔE = E(final) - E(initial)