Chapter 7: Electronic Structure Flashcards
Rutherford’s model did not address
how the electrons occupied the space around the nucleus
initially, it was assumed that electrons held … about the nucleus, leading to the … model of the atom
fixed orbits; planetary
under certain conditions, atoms and molecules emit and absorb energy in the form of
light
in the late 19th century, physicists knew that light could be described as
waves
waves are … in nature: they…
periodic; repeat at regular intervals of both time and distance
any wave is described by its
wavelength, frequency, and amplitude
wavelength (λ, …) is the …
lambda; distance between one peak to the next
in SI system, wavelength is measured in
meters
frequency (v, ..) is the number of …
nu; waves that pass a fixed point in 1 second
the SI unit for frequency si … and is called ..
s^-1; hertz (Hz)
amplitude is the … of a wave
maximum height
height of a wave varies between
+Amax and -Amax
light waves are called… because they consist of …, which are perpendicular to … and to the direction of …
electromagnetic radiation; oscillating electric and magnetic fields; each other; propagation;
the speed at which a wave travels is the product of its
wavelength and frequency
the periodic nature of wave motion is not always
easily seen
the experimentally measured speed of light shows that all electromagnetic radiation travels at the
same speed in a vacuum, no matter what its wavelength
the speed of light in a vacuum is one of the fundamental constants of nature:
3.00 x 10^8 m/s
c=
λv
the amplitude is the vertical …
displacement from the undisturbed medium
the length of time that it takes for one complete wave to pass a point is
deltat
wavelength and frequency are
inversely proportional
the human eye can detect only a very small part of the electromagnetic range, called
visible light
visible light includes wavelengths from … to … nm
400; 700
order of colors for visible spectrum:
VIBGYOR
shorter wavelengths are
higher in energy
amplitude indicates the .. of light source
brightness
gamma and x rays are the
shortest wavelengths (highest in energy)
radio and microwaves are the
longest wavelengths (smallest in energy)
at temperatures greater than absolute zero, matter emits …., and the emission is referred to as a …
electromagnetic radiation of all wavelengths; continuum
not all wavelengths of light are emitted with
equal intensity
the distribution of the intensity of different wavelengths changes with
temperature
in 1900, max planck proposed an explanation of the wavelengths emitted by … that was based on an assumption that violated the classical models of physics
heated objects
planck assumed that the particles of matter in the heated objects were …., and that the amount of energy the particles had was proportional to the …
vibrating back and forth; frequency at which the particles vibrated
planck’s equation
E= hv
h, …., is =
planck’s constant; 6.626 x 10^-34 J * s
because the energy of the vibrating particle has a specific energy, the energy is considered to be
quantized
Einstein applied planck’s equation to … and proposed that light behaves as a …. whose value is directly proportional to the …
light; particle of energy; frequency of the light
Einstein essentially proposed that the energy of light was …, meaning that it could only be a …
quantized; certain amount
photoelectric effect is the process in which electrons are ….
ejected from solid metal when it is exposed to light
each metal has a characteristic …., that is necessary before any …
minimum frequency; electrons are emitted
as the frequency of light increases from the minimum, the kinetic energy of the ejected electrons
alos increases
more intense light does not increase the ….., but it does increase the …
kinetic energy of the electrons; number of electrons emitted
Einstein suggested that light not only had wave properties, but could be viewed as a stream of tiny particles, referred to as
photons
a … with an energy of hv must provide enough energy to …
SINGLE photon; eject an electron
some of the energy, hv0, must be used to overcome the ….
attraction the solid has for the electrons
equation with hvs and ke
hv = hv0 + KE
one photon of light can eject
one electron
increasing the intensity of the light source produces more …, because the number of photons is …
ejected electrons of the same KE; proportional to the intensity
if the energy of the absorbed photon is less than hv0, even with an increased intensity it will only
heat the metal
Einstein’s explanation in conjunction with planck’s theory suggested that each …. was carried by a …
quantum of energy; particle of light or a photon
in the interpretation of the photoelectric effect, electromagnetic radiation is treated as … instead of ..
particles of light (photons); waves
when energy in the form of heat or an electric discharge is added to a sample of gaseous atoms in a process called …, the atoms can emit some of the …
excitation; added energy as light
spectrum: the … of the light as a function of …
intensity; wavelength
a heated solid produces a …., one in which all … are present
continuous spectrum; wavelengths
the light emitted by excited atoms is called a … because it contains light only at …
line spectrum; specific wavelengths
each element produces a line spectrum that is … and different from the spectrum of …
characteristic of that element; any other element
wavelengths of all lines in the spectrums given by the
Rydberg equation
Rydberg equation:
1/λ=R_H (1/(n_1^2 )-1/(n_2^2 ))
n1 and n2 are positive integers with n1 …
< n2
Rh, called the .., has the value of …
Rydberg constant; 1.097 x10^7 m^-1
they hydrogen atom spectrum consists of series of lines that are named after those who discovered them:
Lyman (n1 = 1) Balmer (n1 = 2) Paschen (n1 = 3) Brackett (n1 = 4) Pfund (n1 = 5)
The Rydberg equation accurately predicts the wavelengths ofall observed lines in the
spectrum of hydrogen atoms
the discrete line spectra of atoms suggested that electrons exist in
only certain allowed energy levels
niels bohr proposed a model for the … that accounted for the …
hydrogen atom; observed spectrum of hydrogen
bohr assumed that the electron moved in … around the nucleus
circular orbits
bohr assumed that the electron could have only certain values of
angular momentum
angular momentum:
momentum of a mass moving in a circle
bohr also found that the allowed … and …. are also quantized
radii; energies
En=
(-(2π^2me^4)/h^2)*1/n^2 = -B/ n^2
for En, m is the …., e is the …, h is …, and n is a positive integer that indicates ..
mass; charge of electrons; planck’s constant; electron’s energy level
B=
2.18 x 10^-18 J
bohr concluded that the energy levels of the electron in a hydrogen atom are
quantized
bohr realized that the light emitted by the atom must have energy (hv) that is exactly equal to the difference between the
energies of two of its allowed levels
(bohr) Elight= E2 - E1 =
B/n1^2 - B/n2^2
as the electron and the H+ nucleus move closer together, the atom becomes…, so the energies of all the allowed states have a …
more stable (lower in energy); negative sign
the energy of an allowed state is proportional to …, so the energies of the allowed states get … as n increases
1/n^2; closer together
when an electron goes from one quantized energy state to a lower one, the
difference in energy is released as a single photon
all of the energy released when an atom goes from one allowed energy state to a lower one is contained in a
single photon of light
the electron in the hydrogen atom can also be excited to higher levels by the …
absorption of a photon
the only photons absorbed are those with energy identical to the
energy difference between two allowed states of the atom
the grounds state of an atom is its lowest
quantized energy state
at normal temperatures, nearly all hydrogen atoms are present in the
ground state
thus, the only lines observed in the absorption spectrum of hydrogen atoms are those in the
lyman series
momentum=p=
h/λ
p =
mv
equation–> known as … λ (in terms of momentum)=
de Broglie equation; h/p = h/mv (m is mass, v is velocity)
de Broglie predicted that a particle of matter would have a wavelength that is
inversely proportional to the mass
the davisson-germer experiment, which demonstrated that matter exhibited its …, was a significant step forward in understanding the …
wave properties and particle properties; properties of the electron
diffraction is a property of
waves
de Broglie’s equation explained the assumption of quantized angular momentum of the electron in the hydrogen atom by suggesting that the electron “wave” in an atom must be a …., which is a wave that …
standing wave; stays in a constant position
de Broglie’s restriction for standing wave expressed in this equation:
2πr= nλ
bohr’s treatment of the hydrogen atom cannot be extended to
larger atoms
Erwin schrodinger devised a wave model to describe the
behavior of the electrons in atoms
the electron wave can be described by a mathematical function that gives the …. this function is called a …, represented by the greek letter psi
amplitude of the wave at any point in space; wave function
the square of the wave function gives the … of finding the electron at any point in space
probability
the wave model doesn’t conflict with the Heisenberg uncertainty principle because it does not precisely define the
location of the electron
he values of quantum numbers are related to the … and … of the electron wave and the location of the …
shape; size; electron in 3d space
it is possible to calculate the energy of an electron having each possible
wave function
the angular momentum of the electron is also quantized but this is a …
natural consequence of the wave function
schrodinger’s wave model is a fundamental idea in the theory called
quantum mechanics
the best current description of the electronic structure of the atom treats the electron as a
wave
quantum numbers represented by
n, l, and msubl
the 3d wave function of an electron is called an
atomic orbital
each of the quantum numbers is restricted to certain
whole-number values
n refers to the
principal quantum number
the principal quantum number gives info about the
distance of the electron from the nucleus
all orbitals that have the same value of n are in the same
principal shell
the term principal shell (or simply, shell) refers to all atomic orbitals that hae the same value of n, because they all have approx. the same
average distance from the nucleus
l refers to the
angular momentum quantum number
the possible values of l for a given n are all positive integers from zero up to
n-1
angular momentum quantum number describes the
shape of the orbital
a subshell contains all orbitals that have the
same values for n and l
the notation for a subshell consists of a …, which is the value of the …, followed by a … that identifies the value of the l quantum number
number; n quantum number; lower case letter (s, p, d, or f
s, p, d, and f stand for
sharp, principal, diffuse, and fundamental
ml refers to the
magnetic quantum number
allowed values for ml
-l to l
ml quantum number provides info about the
orientation in space of the atomic orbital
each subshell consists of one or more
atomic orbitals
the fourth quantum number does not directly come from the
wave model
ms refers to the
electron spin quantum number
the allowed values of m are
+1/2 and -1/2
the electron spin does not depend on the values of any of the
other quantum numbers
two electrons that have the same spins are …, whereas electrons with different spins are …
parallel; paired
nodes: regions in space where the probability of finding an electron is exactly
zero
as the principal quantum number increases in value, the average distance of the electron from the nucleus …, and thus the size of the … increases
increases; contour surface
if the principal quantum number is the same, no matter which subshell or orbital the electron occupies, the hydrogen atom has exactly the same
energy
the energy of each wave function for any atomic species containing only one electron is given by
En = -(Z^2B)/n^2 (Z is nuclear charge)
the different subshells within the same shell of a multielectron atom
do not have the same energy
because charges of opposite sign attract each other, the energy of the atom decreases (the atom becomes more …) as the electron
stable; gets closer to the nucleus
energies in multielectron atoms depend on the values of …
both the n and l quantum numbers
in one-electron atoms and ions, the energy depends only on the
value of the n quantum number
the single electron in any one-electron species, regardless of its location or the orbital it occupies, is attracted by the
nuclear charge
the electron-electron repulsions, known as .., reduce the effect of the positive charge of the nucleus on each electron, thus …
interelectronic repulsions; influencing its energy
the net attraction of the nucleus for n electron at any distance r is reduced, or shielded, by the ….
repulsive forces from the electrons between it and the nucleus
effective nuclear charge, Zeff, is the weighted average of the …., after correction for the shielding of nuclear charge by … and the …
nuclear charge that affects an electron in the atom; inner electrons; interelectronic repulsions
electron shielding is the result of the influence of …. on the …
inner electrons; effective nuclear charge
to determine the effective nuclear charge for each electron, we need to know whether the other electrons in the atom are between
it and the nucleus
although the average distances of the 2s and 2p electrons are about the same, the probability that the electron is close to the nucleus is greater for the … than for the …
2s electron; 2p electron
the 2s electron penetrates the electron density of the filled 1s shell more than does the 2p electron, so it is influenced by a
greater effective nuclear charge
the energy of an s electron is … than the energy of a p electron in the same shell
lower
within any shell, the penetration of the s orbital is always greater than that of the … orbitals, which in turn, is greater than that of the … orbitals
p; d
within any shell, the subshells increase in energy in the order of
increasing value of the quantum number l
different interelectronic repulsive forces affect electrons in different subshells, so the energy of an atom depends on
which subshells are occupied
the overlap in the energy of different shells becomes more common as
n increases
energy separation between subshells gets quite small in the higher shells, so small changes int eh shielding effects may cause the energy order to
change from one element to the next
because the energies of different orbitals depend only on the values of the n and l quantum numbers and not on the value of ml, all of the orbitals in a subshell have
exactly the same energy
when orbitals are of exactly the same energy, they are referred to as
degenerate orbitals
pauli exclusion principle: no two electrons in the same atom can have teh
same set of all four quantum numbers
the pauli exclusion principle is the quantum-mechanical equivalent of saying that two objects cannot
occupy the same space at the same time
using the pauli exclusion principle, we find that the maximum number of electrons that can share a single orbital in an atom is
two
two electrons in the same orbital are referred to as an … or …, because they must have different spins
electron pair; paired electrons
when a single electron is in an orbital, it is called an
unpaired electron
the restrictions on the quantum numbers and the pauli exclusion principle determines the capacities of …, …, and …
orbitals; subshells; principal shells
aufbau principle states that electrons are added to the atom one at a time until the
proper number is present
(aufbau principle) as each electron is added, it is assigned the quantum numbers of the
lowest energy orbital available
practically all of the atoms in a sample are in the …at normal temperatures
ground state
if one or more of the electrons is in any other allowed orbital of the diagram, the atom is in an
excited state
the excited state is of …, and the atom tends to return to its ground state by …., often by emitting a …
higher energy; losing energy; photon of light
an excited state is not equivalent to an impossible state, in which ….. of quantum numbers are present
forbidden combinations
two electrons in the same orbital must always have …. , represented by “…” and “…” …
opposite spins; up; down arrows
in an orbital diagram, each orbital is represented by a …, with orbitals in the same subshell shown as …
box; grouped boxes
both … and … are used to represent the electrons in atoms
energy-level diagrams; orbital diagrams
the electron configuration of an atom is …; it does not contain the detailed information about … that an orbital diagram provides
compact; electron spins
whenever electrons are added to a subshell that contains more than one orbital, the electrons enter →…
separate orbitals until there is one electron in each; hund’s rule
two electrons in the same orbital are closer together than they would be if they were in separate orbitals, and they therefore
repel each other more strongly
hund’s rule states that degenerate orbitals are filled with one electron in each before
any electrons are paired
we use hund’s rule to write the ground-state electron configurations and orbital diagrams for the elements iwth atomic numbers
7 through 10
abbreviated electron configuration: uses … to represent the partial electron configuration up to the number of electrons for that gas
noble ass
abbreviated electron configurations are more convenient for expressing the electron configurations of
heavier atoms
anomalous electron configuration are configurations that are the
exceptions
the anomalous electron configuration leads to a combination of either … or a … and a …
two half-filled subshells; half-filled; completely filled subshell
we cannot predit which atoms will ahve
anamolous electron configurations in advance
the total electronic energy of the atom is … in an anomalous configuration in comparison with a …
lower; “normal” electron configuration
