Ch. 7 Quantum Theory and the Electronic Structure of Atoms

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Speed of any form of radiation will be given by the product of_

-the wavelength and the frequency (m/cycle) X (cycles/s)= m/s (unit of speed)

what are the shortest waves? (include their frequency)

-they have the highest frequency -gamma rays

energy is a certain_. why?

-wave -when it leaves it source it affects the space around of it in an osilation motion, which we call waves

what formula describe all electromagnetic radiation?

All electromagnetic radiation wavelength x frequency = c (speed of light)

what Planck could not explain about his theory?

At the time Planck presented his theory, he could not explain why energies should be fixed or quantized in this manner (hv, 3 hv, 2 hv....)

how to determine the speed of the wave? (include the symbol for it?) (equation)

The speed (u) of the wave = wavelength x frequency

describe the frequency and energy characteristics when wavelength is shorter?

Wavelength is shorter=higher frequency=higher energy

light passing through 2 adjacent slits

constructively amplitudes add, waves in phase destructive amplitudes cancel, waves out of place

wave

continuously repeating change (oscillation) in matter or in a physical fiels

electric field

electrically charged particles experience a force

Entire range of wave lengths is called _

electromagnetic spectrum

radiation is a form of_

energy

what is a property of matter?

energy

electromagnetic radiation

energy in the form of oscillation in matter or in a physical field

according to the quantum theory how energy is emitted? (in terms of hv)

energy is always emitted in integral multiples of hv (ex: hv, 2hv, 3hv...) but never 1.67hv, or 4.89 hv

planck basic idea

energy of an atom is quantized; can only contain certain fixed quantities not continuous; each change in energy results from gain or loss of quanta (packet of energy)

all em radiation consists of

energy propagated by electric and magnetic fields

electric and magnetic fields alternately

increase and decrease in intensity as they move

electromagnetic radiation

is the emission and transmission of energy in the form of electromagnetic waves

what is another important property of the waves?

is their speed

what the speed of a wave depend on? (2)

it depends on the type of wave and the nature of the medium through which the wave is traveling (for example, air, water, or a vacuum)

wavelength units?

it is usually expressed in units of meters, centimeters, or nanometers

threshold frequency

light must have a minimum frequency or not current flows

electrons determine

many of the chemical and physical properties

absence of time lag

regardless of intensity, no time lag with certain lights because intensity doesn't matter just frequency of light

radiation with high frequency has

short wavelength and high energy

emission of electrons depends on

single photon having sufficient energy to dislodge a single electron

diffraction

spreading out of waves when they encounter an obstruction or opening the size of the wavelenght

what is the relation between frequency and the energy associated with radiation?

the higher the frequency, the more energetic the radiation

properties of atoms and molecules are not governed by_

the same physical laws as larger objects

quantum mechanics

theory that explains the behavior of the extremely small

in vacuum all types of radiation

travel at speed of light

hertz

unit of frequency

magnetic field

does no worked on charged particle; where an area object exhibits a magnetic influence

particles vs. waves

don't undergo refraction when passing through dif mediums; in slit experiment pass straight through

Now compare 2 beams of light having the same frequency (greater than the threshold frequency) but different intensities when directed against the metal

-The more intense beam of light consists of a larger number of photons; consequently, it ejects more electrons from the metal's surface than the weaker beam of light -Thus, the more intense the light, the greater the number of electrons emitted by the target metal -The greater the frequency of the light, the greater the kinetic energy of the ejected electrons

what Max Planck did? (what he did, what he discovered, what physicist assumed in that time?) How he called his theory?

-While analyzing the data on radiation emitted by solids heated to various temperatures, Planck discovered that atoms and molecules emit energy only in certain discrete quantities, or "quanta" -Physicists had always assumed that energy is continuous and that any amount of energy could be released in a radiation process -His theory was called: Plank's quantum theory

photoelectric effect

-a phenomenon in which electrons are ejected from the surface of certain metals exposed to light of at least a certain minimum frequency, called the threshold frequency

what did Maxwell's theory stated?

-an electromagnetic wave has an electric field component and a magnetic field component -these 2 components have the same wavelength, frequency, and amplitude, and hence the speed, but they travel in mutually perpendicular planes (oscillate in 2 mutually perpendicular planes)

how atoms are arranged in solids (especially metals)? who gave an explanation to this arrangement (explain what he said)?

-atoms are fixed in place and they vibrate or oscillate at place at frequency depends on particular metal that you are dealing with -Plank's equation explained the behavior of solid metals (E=h X frequency) -He had to embrace the odd idea that atoms in solids will have certain fixed amount of energy (quantize the energy) -Fixed defined amount of energy to metals (positive values only)

starting with this hypothesis, Planck had no trouble correlating the experimental data for_. They all supported the_

-emission by solids over the entire range of wavelengths -They all supported the quantum theory

what is the value of Planck's constant? (include symbol)

-h 6.63 X 10⁻³⁴ J∙s

the _ the frequency is the_the energy associated with the light. what happens in the opposite case?

-higher -greater -the lower frequency is the lower energy associated with the light

The number of electrons ejected (in the photoelectric effect) is proportional to the_, but the _were not. Below the_no electrons were ejected no matter how intense is the light

-intensity (or brightness) of the light -energies of the ejected electrons -threshold frequency

what is the significance of Maxwell's theory?

-is that it provides a mathematical description of the general behavior of light -In particular, his model accurately describes how energy in the form of radiation can be propagated through space as vibrating electric and magnetic fields

amplitude

-is the vertical distance from the midline of a wave to the peak or trough; brightness of wave

what the amplitude determines of light? what about colors?

-it determines the intensity of light -the farther it is from the middle, the brighter the light will be -the closer to the middle, the duller the light will be -differentiate between colors by amplitude of wavelength

frequency units?

-it is measured in hertz (Hz), where 1Hz=1cycle/s 1/s or s^-1 (1 per second) ex: 25/s or 25 s^-1 (25 per second)

wavelength (symbol, definition, units)

-lambda symbol -is the distance between identical points on successive waves. -distance in one cycle (m/cycle)

electromagnetic waves travel at what speed? (include name and symbol) in which medium? how it travels in another mediums?

-Speed of light (c) in vacuum = 3.00 x 10⁸ m/s -This speed differs from one medium to another, but not enough to distort our calculations significantly

what is the relation between frequency and wavelength?

-The higher the frequency, the shorter the wavelength will be -If reduce its wavelenght by ½, its frequency will increase by factor of 2 -Reciprocal relationship between frequency and wavelength

wavelength lambda

distance between any two adjacent identical points of wave

what determines the amount of energy a compound has?

each compound has certain amount of energy that depends on the way it is compose

how gamma rays result?

from changes within the nucleus of the atom

How Einstein called the particles of the stream if light?

photons

electromagnetic radiation is emitted as well as absorbed in the form of_

photons

what type of light is white light?

polychromatic light

Planck's theory is called_

quantum theory

what are the longest electromagnetic waves?

radio waves

what is the visible light color with the highest energy?

violet

By using Einstein theories at the time, light has both_ (2 natures)

wave nature particle nature

visible light ranges from a_

wavelength of 400 nm to 700 nm

visible light range

400-750 nm

electromagnetic spectrum

range of frequencies or wavelengths of electromagnetic radiation

what is the visible light color that has the lowest energy?

red

what are other examples that can be quantized besides energy? (include how they are related)

*There could be only whole-number multiples* -electric charge of electrons -Matter (number of electrons, protons, and neutrons, and atoms must be integers) -monetary system (penny) -living systems (born organisms)

which rays have the shortest wavelength? what about its frequency?

-gamma rays -highest frequency

the energy (E) of a single quantum of energy is given by_ ( 2 formula)

E=hv E= energy h= Planck's constant v= frequency of radiation E=h (c/wavelength) c= speed of light

what happens if we pass light through a prism?

If you pass white light through prism, the light separates into 7 colors

who solved the problem of heated solids?

Plank

polychromatic light

Light of many different colors

monochromatic light

Light of specific color (single)

The new era of physics started in 1900 with who?

Max Planck

how are the shorter, visible light waves produced?

by the motions of electrons within atoms and molecules

what is the magnitude of the speed of light?

c= 3.00 X 10⁸ m/s

work function

a certain amount of energy is needed to eject the electron

wave

a vibrating disturbance by which energy is transmitted

electromagnetic wave

a wave that has an electric field component and a mutually perpendicular magnetic field component

wave theory associates energy of light with

amplitude

how the various types of electromagnetic radiation differ? (2)

by having different wavelength and frequency

where are radio waves emitted?

by large antennas, such as those by broadcasting stations

what the measurements taken during the 19th century showed about how much energy can an object emit? what theory and law could not explain this?

measurements taken in the latter part of the nineteen century showed that the amount of radiant energy emitted by an object at a certain temperature depends on its wavelength -Attempts to account for this dependence in terms of established wave theory and thermodynamic laws were only partially successful -Some theories could explain the short wavelengths dependence and other the long wavelengths dependence, but seemed that something fundamental was missing of the classical physics laws

speed of wave changes when

moves from different medium; refraction through water

the wavelength of electromagnetic waves is usually given in which units?

nanometers (nm)

intensity relates to

number of photons

frequency

number of wavelengths of a wave that pass a fixed point in one unit of time usually a second

photon

particle of light

what are the 2 parts of the wave?

peaks troughs

early ideas of quantum theory led to a new era in physics called_

quantum mechanics

threshold frequency

-1 type of energy will make electrons break free and that is the minimum energy need to put (certain minimum frequency)

what mystery Albert Einstein solved? (regarding the quantum theory)

-Albert Einstein used the theory to solve another mystery of physics, the photoelectric effect

what was well established in the 19th century? what was not known?

-Beginning of 19th century, people knew energy (radiation) traveled in waves -relates with intensity of light and speed of light (properties of wave length) -know speed of light -wave theory was very established -Mysteries that the wave theory could not explain

what was the earlier attempt to explain the way atoms and molecules are? (describe it, what physicists could do about this and what they could not do)

-By assuming that molecules behave like rebounding balls, physicists were able to predict and explain some macroscopic phenomena, such as the pressure exerted by a gas -However, this model did not account for the stability of molecules; it could not explain the forces that hold atoms together

how the electromagnetic radiation travels?

-Combination of movements, they oscillate and move through space in a very synchronized manner→thrust contacts with crest -they oscillate in 2 mutually perpendicular planes -All radiation travel with speed of light

who's explanation of what is another step toward the development of the quantum theory? To explain experimental observations, he suggested that _

-Einstein's explanation of the photoelectric effect -Einstein suggested that light behaves like a bundle of particles called photons

explain the particle-wave duality (include the dilemma of this)

-Einstein's theory of light posed a dilemma for scientists -On the one hand, it explains the photoelectric effect satisfactorily -On the other hand, the particle theory of light is not consistent with the known wave behavior of light -The only way to resolve the dilemma is to accept the idea that light possesses both particle-like and wavelike properties -Depending on the experiment, the light behaves either as a wave or as a stream of particles. This concept is called the particle-wave duality

describe how electrons are found in a metal and what is required to remove them from the metal?

-Electrons are held in a metal by attractive forces, and so removing them from the metal requires light of a sufficiently high frequency (which corresponds to sufficiently high energy) to break them free -Shining a beam of light onto a metal surface can be thought of as shooting a beam of particles (photons) at the metal atoms -If the frequency of photons is such that hv is exactly equal to the energy to knock the electrons be knocked loose, but they will also acquire some kinetic energy -This situation is summarized by the equation hv= KE (kinetic energy of ejected electron) + W (work= measure how strong electrons are held in the metal) -The more energy the photon (the higher frequency), the greater the kinetic energy of the ejected electron

what were the 3 problems that could not explained by physicists?

-Heated solids -photoelectric effect -line spectra of atoms

explain in more detail the mystery of the heated solids and what wave theory could not explain.

-If have chunk of metal, if were to heat it, when temperature get to 1000K it begins to emit visible light (dull red radiation) -when continue heat it nothing happens until 5000K -between 1000 and 1500 continues dull red -15000k and 20000k it is pink color -20000k it begins to emit quite light -Wave theory could not explain that because amount of energy changes continuously→there should be a change of the color of light that the object emits but the object did not change of color until specific amount of K

waves are characterized by their _(3)

-Length (wavelength) -height (amplitude) -frequency

what James Clerk Maxwell proposed?

-Maxwell (1873), proposed that visible light consists of electromagnetic waves

How Planck solved the problem of heated solids? (include what the classical physics thought about this phenomena)

-Planck solved the problem with an assumption that departed drastically from accepted concepts -Classical physics assumed that atoms and molecules could emit (or absorb) any arbitrary amount of radiant energy -Planck said that atoms and molecules could emit (or absorb) energy only in discrete quantities, like small packages or bundles -Planck gave the name quantum -Energy (light) is emitted or absorbed in discrete units (quantum).

Describe the machine that studies photoelectric effect?

-light of certain frequency falls on a clean metal surface -Ejected electrons are attracted toward the positive electrode -The flow of electrons is registered by a detecting meter -Light meters used in cameras are based on the photoelectric effect -plate of metal of potassium and put it in chamber in vacuum= 2 wires that are connected to opposite poles to link to a meter -when you shine a monochromatic light on metal(light of 1 color) let electrons break free of the metal -so electrons very quickly attracted to the positive charge and current will flow

quantum

-name given by Planck -the smallest quantity of energy that can be emitted (or absorbed) in the form of electromagnetic radiation -discrete units

frequency (symbol, definition, and unit)

-nu (v) -is the number of waves that pass through a particular point in 1 second (Hz = 1 cycle/s). -number of waves that pass a specific point in space per unit time (seconds)

which wave has the longest wavelength? what about its frequency?

-radio waves -lowest frequency

what is the visible light color that has the longest wavelength? (indicate the value)

-red 700 nm

analyze: speed of wave= wavelength X frequency

-the wavelength expresses the length of a wave, or distance/wave -the frequency indicates the number of these waves that pass any reference point per unit of time, or waves/time -Thus, the product of these terms results in dimensions of distance/time, which is speed: (distance/time)= (distance/wave) X (waves/time)

wavelength can be measured between_(3)

-two troughs -two peaks -any 2 point that are identical

what are the 3 electromagnetic waves have a high-energy radiation? why?

-ultraviolet radiation -X rays -gamma rays -because the higher the frequency, the more energetic the radiation

what is the visible light wave color that has the shortest wavelength? (indicate the value)

-violet 400 nm

what are 3 types of waves?

-water waves -sound waves -light waves

the photoelectric effect could not be explained by the_ (explain why). However, Einstein made an extraordinary assumption_

-wave theory of light. According to wave theory, no matter what type of light shine to metal electrons will break free. However, electrons will break free only with specific light. People tried to exposed the metal with a lower light→regardless of what they did only one light will make the electrons eject from the plate and was the buttle light(?) -He suggested that a beam of light is really a stream of particles -Using Planck's quantum theory of radiation as starting point, Einstein deduced that each photon must possess energy E, given by the equation E= hv (where v is the frequency of light) -It is light itself that it is quantized→he said light exists as particles because those particles have specific electromagnetic energy associated with them -He said that electron will be ejected only if the light shine to metal has specific frequency (threshold frequency)

what are the 3 properties of waves?

-wavelength -frequency -amplitude

each type of radiation is spread over a specific_(2) in the electromagnetic spctrum

-wavelengths and frequencies

Describe what happen when the light of specific frequency is directed toward the metal at the molecular level

-when photon of light hits the electrons, it becomes pure energy, electron absorbs energy and break energy bonds and we say photon is absorbed -Photon will be converted into energy when hit electron that is sufficient to make the electron to break connections to break free

what happen when a solid is heated? (give 2 examples)

-when solids are heated, they emit electromagnetic radiation over a wide range of wavelengths -ex: dull red of electric heater and bright white of a tungsten ligthbulb

can you list from highest to lowest energy radiation in the electromagnetic spectrum?(7)

1. gamma rays 2. X rays 3. Ultra violet rays 4. Visible light 5. Infrared 6. Microwave 7. Radio waves

conversion factor of 1 nanometer to meter and viceversa?

10^9nm= 1m 1nm= 10^-9 m


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