chapter 4
what is the visible region?
400-700nm wavelength
where is hydrogen atom emission spectrum shown? What does this show?
410nm, 434nm, 486nm, and 656nm only certain energies are possible. that is the election energy levels are quantized. In contrast of any energy levels were allowed, the emission spectrum would be continuous
What is the Lyman series?
all electrons transitions that end on the first energy level. as there is a large difference in energy between the first and second energy levels, these six lines are all high energy which puts them in the UV range.
What has much of our present understanding of the electronic structure of an atom come from? What does this mean we need to do?
analysis of the light absorbed or emitted by substances-> We need to learn more about light
what is the equation that represents the relation between wavelength and frequency
c= νλ ν=c/λ λ=c/ν
what is delta E?
change in energy
The particle nature of electron could not explain what?
different characteristics of an atom
What does E equal?
energy in joules
what does sunlight consist of? What are characteristics of each color of light?
it consists of light with continuous range of wavelengths of frequency? the wavelength and frequency are characteristics
what happens when an electron gains energy?
it gains photons of specific energy and move to a higher energy level, it them releases this energy back in the form of a photon that we see as light or any other form of EMR
what does it mean that electromagnetic radiations carry energy through space?
it is also called radiant energy
what happens when sunlight passes through a prism? what are the wavelengths a part of?
it is separated into specific wavelengths that are part of hydrogen's line emission spectrum (the line at 397 nm is the ultraviolet is in the ultraviolet and is not visible to the human eye)
what happens when atoms first absorb energy?
its electrons jump to higher energy levels
what unit is used for mass in λ=h/mv?
kg
will any frequency of light cause the photoelectric effect?
no: red light (ν=4.3x10^14) will not cause the ejection of electrons from potassium no matter how intense the light, yet even a very weak yellow light (ν=5.1 x10^!4) shining on potassium begins the effect
how many d orbitals are in n=1,n=2? Where are the d orbitals first occurring? how many d orbitals are there?
none-d orbitals first occur in n=3 there are 5 d orbitals
when can the location of an electron be determined? what happens after the impact?
only if it is struck by another particle such as photon. after the impact, the velocity changes
what is a quanta?
packet-> particle (cant have wave in a packet?)
what color glow does exited hydrogen atoms emit?
pink
what is wavelength represented on?
the Greek letter lambda λ
What is frequency represented by?
the Greek letter nu (ν)
What is a quantum?
the amount of energy an electron needs to make such a jump between energy levels
What is an orbital? Is the orbital defined or undefined?
the area where probability of finding an electron is high. The boundary of an orbital is not perfectly defined
what is the quantum theory?
the description of the atom built on the wave properties of electrons
what is needed to understand hydrogen atom emission spectrum?
the difference among the continuous spectrum an the line spectrum
what is the energy of light is equal to?
the difference between the original and final energy levels of the electron
what happens when sunlight passes through a prism?
the different wavelengths separate into a spectrum of colors
what are valance electrons, and what are they responsible for?
the electrons in the outermost principal energy level of an atom. they are responsible for characteristic chemical properties.
is the emission spectra of elements similar or different from the white light spectrum?
the emission spectrum of elements are quite different from the spectrum of white light?
What is a continous spectrum?
the kind of spectrum when each color blends into the next in order is called continuous spectrum
what does E equal in E photon=hν
the minimum amount of energy required by an electron to move
What is frequency?
the number of waves to pass a given point in one second
what can be collected if the energy emitted is known?
the wavelenth delta E=hν=h.c/λ
What do all forms of electromagnetic radiation have in common?
they all form the electromagnetic spectrum
what is the relation between the energy of the wave and the frequency?
they are directly proportional- frequency increases=energy increases
what is the relation between wavelength and frequency?
they are inversely related-higher wavelength=lower frequency
what does each line in a line spectrum correspond to? what does this mean?
they correspond to an exact frequency, therefore an exact energy is emitted from the atom
what happens when atoms that absorbed energy when come back to ground state?
they emit energy in the form of light
can position and velocity of an electron be measured?
it can be measured, but the precision of these measurements is limited
What values are in the electron spin QN, what does it mean, and what is the symbol?
(ms) has 2 values (+1/2 and -1/2) which means electrons can spin in one of two opposite directions. since a spinning charge produces a magnetic field, the two opposing spins produce oppositely directed magnetic fields.
what does the principle quantum number describe, assigned, and say with the value? What is its symbol?
(n) describes the energy level that the electron occupies, assigned a positive integer, and the larger the value, the farther away from the nucleus, and the higher the energy
what fills first? n+1 or nd
(n+1) orbitals always fill before nd orbitals
what fills first? n+2 or nf
(n+2) orbitals always fill nefore nf orbitals
what did Einstein suggest in 1905?
(radical idea at the time) that 1) electromagnetic radiation has a dual nature, that is, it can behave as a particle as well as a wave 2) although light exhibits many wave like properties it can also be thought of as a steam of particles
what does the azimuthal quantum number describe, assigned, and say with the value? What is its symbol?
(ℓ) value 0- (n-1) shape of an atomic number (l cant be greater than n) the value corresponds to an orbital
What is the Aufbau principle? what is the lowest energy sublevel within the principle energy levels? what is used to represent an atomic orbital?
-Electrons enter orbitals of lowest energy first -s sub level is lowest energy principle energy level. -box is used to represent an atomic orbital
what does the quantum model have in common with Bohr's model? What is different?
-Like Bohr, the quantum mechanical model predicts quantized energy levels for electrons -Unlike Bohr, quantum mechanical model does not describe the exact path of an electron takes around the nucleus (orbit) rather that it reveals in a very complex wave motion -electron does not travel in an orbit, but in an orbital (electron cloud)
what are the three characteristics of electromagnetic radiation?
1) move through a vacuum at the speed of lght (3.00x10^8 m/s) 2) wavelength 3)frequency
what are the characteristics of electrons moving between energy levels?
1) only electrons going from a higher to lower energy level emit light or other EMR 2) each transition gives a specific line in the spectrum of that atom
what did German physicist Max Plank propose?
1)a hot object does not emit electromagnetic energy continuously, as would be expected, if the energy emitted were in the form of waves 2) the object emits energy in small specific amounts called quanta 3) a quantum is the minimum amount of energy that can be lost or gained by an atom 4) E=hv
what are the two properties of electrons
1)electrons have properties of particles a)as evidence by their behavior in cathode-ray tube b)and their ability to jump and fall among high and low energy orbitals 2)electrons have properties of waves electrons have tiny wave lengths on the order of 10^-10m
What did Bhor propose?
1)electrons in an atom can reside only in certain orbits (energy levels) 2)electrons in a given orbit have a fixed energy, therefore, they do not lose energy and fall into the nucleolus. the energy levels within an atom are like runs/steps of a latter rather than a planet 3) energy levels close to the nucleus lave lower energy 4) an electron mus gain or lose the right amount of energy to move from one energy level to another 5) the amount of energy gained or lost by every electron is not always the same because energy levels are not equally spaced
what is an orbital?
1)orbital is a space where probability of finding an electron is high 2) can be though of as a blurry cloud of negative charge 3)can be compared to a fan blade in a moving fan 4)electron cloud is more dense where the probability of finding and electron is high and less dense where the probability is low 5)a line is drawn around the electron cloud so that electron is inside the line 90% of the time 6)all based on complex mathematical models
in quantum theory, what is each electron in an atom is assigned? what do three of them give? What does the fourth one give?
1)set up of four quantum numbers 2)three of these are like co-ordinates on a map and given the location of the electron 3)gives the orientation of an electron
what are the three main points made by Plank?
1)the amount of radiant energy (E) absorbed or emitted form an object is proportional to the frequency of radiation 2)it is not possible to increase or decrease the energy of a system by a fraction of hν 3)small energy change involve the emission of low frequency radiation and high energy involves an emission of high frequency radiations
what units are used to measure frequency?
1/sec (s^-1) or hertz
what unit is used for joules?
1kg m^2/s^2
what does 1 nm equal?
1x10^-9m
How many electrons can each orbital hold?
2 electrons
What was used to explain the characteristics of the atom?
A fundamentally different view (wave nature)
What was wrong with Rutherford's model?
As electrons radiated, their energy would be lost, and they would not be able to stay in orbit. The electrons would spiral towards the nucleus and collapse into it. The atom would be destroyed in a billionth of a second, but most atoms were known to remain stable for thousands of years
what were the shortcomings of Bohr's model?
At first, his model appeared promising-his calculations agreed with the hydrogen emission spectrum 1)his model didn't work with atoms other than hydrogen 2) there were attempts to adapt it with elliptical obits, but it was concluded that his model is fundamentally incorrect-the current theory of atomic structure is in no way derived from the Bohr 3)electrons don't move around the nucleus in circular orbits 4)however, Borh's model paved the at for later theories
Who was Niels Bohr?
Danish physicist and a student of Rutheford
what is the energy necessary to completely remove an electron from the first shell of a hydrogen atom?
E=1320 kJ/mol /n^2
what does h equal?
Planck's constant 6.626x10^-34 js (joules/sec)
what colors are in the visible light spectrum? Which color has the shortest/longest wavelength and the lowest/highest energy?
ROYGBIV- red has the longest wavelength and lowest energy, and violet has the shortest wavelength and highest energy
what does it mean that classical physics showed all accelerating charged particles radiate energy
Therefore, the circulating electrons in Rutherford's planetary model must also radiate energy
what is visable light
a kind of electromagnetic radiation
what had to happen since electrons have dual properties of both particles and waves
a new model for atomic structure had to be developed
what is a photon
a particle of electromagnetic radiation having zero mass (the mass is too small to measure) and carry a quantum of energy
What is a line spectrum?
a spectrum that contains only certain discreet wavelengths
what did the quantum model treat the electron like?
a wave
what was discovered with more investigation into line emission spectrum? what are they named after?
additional series of lines in the infrared and ultraviolet regions, named after their discoverers-lyman balmer ,and paschen
what is the configuration of lanthanum, and where are electrons filled after?
after lanthanum which has the configuration [Xe] 6s^2, 5d^1, 14f electrons are filled in lanthanide series
What is the Balmer series?
all electron transitions that end on the 2nd energy level. this gives only five possible lines, 4 in the visible light spectrum and only barely in UV
What is the Paschen series?
all electron transitions that end on the 3rd energy level all of these transitions involve small energy changes, therefore, these 4 lines are all in the infrared region of the spectrum
what are the characteristics of the d-orbital?
dumbell shaped with a doughnut around the middle, five orbitals, hold max 10 electrons, energy more than s and p orbitals
what are the characteristics of the p-orbital?
dumbell shaped, there are three p orbitals, can hold maximum of 6 electrons, and have a higher energy than s-orbitals
what does delta e equal?
ef - ei
what did we learn from theorist up to bohr?
electrons, nucleuses, and energy levels
what was bohr able to explain?
emission spectrum of hydrogen
what is the energy of a photon that falls from an excited to ground state?
equal to the difference in energy between the initial and final state
what does the quantum theroy show?
even with sophisticated technology, it will never be possible to measure both the electron's position and velocity simultaneously
what is the expected and actual configuration of copper?
expected: [Ar] 4s^2 3d^9 actual:[Ar] 4s^2 3d^10
what is ν?
frequency of radiation emitted?
what are types of electromagnetic radiations?
gamma, x, ultraviolet, visible light, infrared, micro, radio
what does passing the light emitted through a prism do?
gives the atomic emission spectrum of the element
What did Einstein call light that exhibits many wave like properties and is also thought of as a steam of particles?
he called these particles photons
What are core electrons?
inner electrons
when was the quantum introduced? by who?
introduced by Erwin Schrodinger in 1926
what eventually happens to an excited state atom? what do they emit?
later atoms return to the ground state, by emitting energy, they absorbed, in the form of light
What is wavelength?
length between two adjacent crests
what is the order of the energy levels in hydrogen?
lyman, balmer, and paschen series
what unit is used for velocity(seed) in λ=h/mv?
m/s
what are m and v in λ=h/mv
mass and velocity
what units are used to measure wavelength?
meters
is it possible to know the location and velocity of an electron?
no
What is the Pauli Exclusion Principle? what does it also mean?
no more than two electrons can be found within a particular orbital and they must have opposite spins. therefore, no two electrons can have the same set of QN
What did Bhor do?
proposed a new model
what does the magnetic quantum number show/represent and mean? What is its symbol?
relates to the orientation of the orbital in space relative to the nucleus (-l-+l)
what are the characteristics of the f-orbital?
seven orbitals, max of 14 electrons, and highest in energy
will and electron always occupy 4f first? why?
sometimes one electron occupies a 5d instead of a 4f orbital because the enrgies of 4f and 5d are very similar
What does C represent?
speed of light
what are the characteristics of the s-orbital?
spherical in shape, lowest in energy, and can cold max of 2 electrons
what is the emission spectrum unique to?
that element (fingerprint
what did Bhor's model show?
that energy of a n electron in an atom is quantized
2px
value of n, orientation in space, value of 1, there are no p orbitals
what is the photoelectric effect explained by?
wave nature
what behavior is exhibited by electromagnetic radiation as it travels through space
wavelike behavior
what is the ground state of an atom?
when all the electrons are in the lowest possible energy levels
What is Hund's rule?
when electrons occupy orbitals of equal energy, one electron enters each orbital until all the orbitals contain one electron with spins parallel. when all the orbitals with same energy have one electron each, electrons start to pair up. (fill then pair)
what happens in the photoelectric effect?
when light shines on them, metals eject electrons called photoelectric electrons
What is the excited state of an atom?
when the atom absorbs energy so that its energy so that its electrons are boosted to higher energy levels
what is the difference between white light and the emission spectra? what is the name of the spectrum given off by the emission spectrum?
white light gives a continuous spectrum while atomic emission spectrum gives few colored lines separated with dark spots. this kind of spectrum is called line spectrum
What is the Heisenberg Uncertainty Principle? what does the quantum theory show on this topic?
you can never know exactly where an electron is if you know exactly how fast it is moving, or you can never know exactly how fast an electron is moving if you know exactly where it is. quantum theory shows there is a limit to what we can know inside an atom.
What are the values equal to in the azimuthal QN?
ℓ=0->s->1->2 s-name of orbital 1-number of orbital 2-number of electrons ℓ=1->p->3->6 ℓ=2->d->5->10 ℓ=3->sf->7->14
