CH 5 Electrons in Atoms Flashcards
Bohr’s atomic model
- physical model, upgrade from planetary
- incorporated new discoveries into Rutherford’s nucleic model (like photoelectric effect)
- based off of the simplest element, HYDROGEN**, didn’t explain those with more than one electron
theorized that…
- electron is only found in specific orbits
- each possible electron is quantized (has specific amount of energy
- they must give off or gain a quantum in order to change their orbit
- the electrons CLOSEST TO THE NUCLEUS ARE LOWER ENERGY, THE ELECTRONS FURTHEST ARE HIGH ENERGY
Schrödinger
*takes Bohr’s model from HYDROGEN to everything else
- created quantum mechanical model EQUATIONS based off of later inconsistent evidence with Bohr’s model
- ‘quantum mechanical model’ derived from equations
- mathematical rather than physical
- most modern description of atoms and their electrons
- if you GRAPH equation, you make orbital shapes
- like Bohr’s, electrons are quantized
- UNLIKE Bohr’s, the path an electron takes around the nucleus is non-exact, and uses PROBABILITY that an electron is in any location (like windmill blades)
what are Bohr’s quantized orbits similar to?
PRIMARY ENERGY LEVELS, rungs on a ladder, unevenly spaced at times (need different quantums)
what couldn’t Rutherfords’ model explain?
the changing of physical properties elements underwent in fire, etc. (what we now know as chemical reactions, interaction of electrons)
electron cloud
represents the locations where an electron is likely to be found in a certain volume of space; it is not possible to know where one is in the cloud at any moment
- high density= higher probability, low density= low probability
- no boundary, as electron COULD be very far from nucleus, usually limited to location 90% of the time
solutions to schrödinger’s equation give…
the energy level an electron can have
Light calcs
E=hv
C=lambda v
Aufbau principle
electrons fill from lowest to highest energy level
(lowest energy first)
sublevel orbitals always equal (4s #1 = 4s #2)
Pauli Exclusion Principle
each orbital describes 2 electrons
must have opposite spins
Hund’s Rule
everyone gets one electron before anybody at the same energy level gets 2
issues w/ Rutherford’s model
doesn’t account for:
- proton/e- attractions
- metals changing color when heated (iron which is brown going from red to white)
- solutions showing bright line spectrums when heated
define energy level
an area around the nucleus where orbitals exist
define orbitals
a place in an energy level where there is a chance of locating two electrons (technically electron cloud OF the nrg level)
define orientation
a different location of the orbital and their electrons
what is the difference between 1s v. 2s
2s occupies more volume, but can hold same number of electrons
what is the purpose of electron configuration exceptions?
to create a more stable atom
number of orbitals formula
n^2
number of electrons formula
2n^2
Hantaro Nagaoka
suggests that an atom has a central nucleus and that electrons move in rings like those of Saturn
Louis de Broglie
proposes that moving particles like electrons have some properties of waves
In a atom, electrons and the nucleus interact to…
make the most stable arrangement possible
the y axis of an aufbau diagram is
increasing energy
exceptions
column 6, 11
Isaac Newton
tried to explain behavior of light by assuming it consists of particles
by 1900, scientists had evidence that light was made of
WAVES
waves of light have certain properties
amplitude, wavelength, frequency
amplitude
height from zero to crest
frequency
m/s also Hz or s-1
wavelength
m
electromagnetic radiation
includes visible light, UV, X-rays, gamma
3.00 x 10^8 m/s (C)
speed of light
when sunlight (white) passes through a prism…
it separates into a spectrum of colors
violet light
400 nm -470 nm
blue light
470 nm - 530 nm
green light
530 nm - 580 nm
yellow light
580 nm - 620 nm
orange light
620 nm - 700 nm
red light
700 nm
radio
100-1 m
micro
1^-1 to 1^-3
infared
10^-4 to 10^-6
UV
10^-7 to 10^-10
x-rays
10^-11 to 10^-12
gamma
10^-13
atomic emission spectra
BRIGHT LINE (when an electric current is passed through an element, the electrons are energized, then emit light)
when electrons gain energy
they move up to higher energy levels
when electrons lose energy by emitting light
they return to lower energy levels
regular light put through a prism creates a…
rainbow
energized light (helium lamp) put through a prism creates an…
atomic emission spectrum made up by several specific lines of color
no two element’s atomic emission spectra are
the same; therefore they can be used to identify elements (often used to analyze stars/astronomical bodies)
scientists who discovered E=hv
Max Planck;
trying to understand color changes while heated, could explain if he assumed energy of a body changes in small discrete units (quanta)
*quantization of energy
h, or 6.626 x 10-34 JxS is called
Planck’s constant
the energy of a quantum equals
hv
a small energy charge discharges or absorbs
low-frequency radiation
a large energy change discharges or absorbs
high-frequency radiation
_______ used Planck’s quantum theory to explain ____
Albert Einstein; the photoelectric effect
the photoelectric effect
electrons are emitted when a specific light, at or above the threshold frequency, shines on a metal; classical physics (light=energy in waves) could not explain
threshold frequency
the frequency a light must reach to emit electrons from a metal (photoelectric effect);
above it, the electrons travel faster
Albert Einstein’s explanation of the photoelectric effect
he proposed that light could be described as quanta of energy that behave like particles, or PHOTONS quantized according to Planck’s forumla
photons in a monochromatic (same frequency) beam have
the same energy
electrons are ejected when
freuquency/energy are too low
light behaves as
waves and particles
when an electron has its lowest possible energy it is in its
ground state
the step of an emission of an electron is also known as
electronic transition
the light emitted by an electron moving from a HIGHER to a LOWER energy level has frequency ______ to the energy change of an electron.
DIRECTLY PROPORTIONAL
this causes
the lines of specific frequency in an atomic emission spectrum
Warner Heisenberg
uncertainty principle (we can know either velocity or location of electron, not either, since we must trap it an a magnetic field to find location)
Bohr’s model explains the _______ of all atoms because______
atomic emission spectra; it predicts the quanta of energy (light) atoms give off as they jump between energy levels (energized)
more closely spaced spectral lines mean
energy levels are closer together, occurs at increased values of n
there is a limit to the frequency of emitted light because
with a high enough energy, the e- completely escapes atom
Clinton Davisson and Lester Germer
confirmed de Broglie’s theory of matter waves by showing the reflections of electrons off of metals that acted like waves (caused by X-rays)
wavelike properties of electrons are useful because_____
they are used in electron microscopes to show very small objects
de Broglie’s equation
predicts that all moving objects have wavelike behavior, but mass must be very small for the wavelength to be large enough to observe (must travel at much higher velocity)
-set stage for new way to describe motion of subatomic particles…QUANTUM MECHANICS versus classical mechanics for big things, quantum is used on small things which act like waves and particles)
atomic spectra are produced as
atoms emit light as excited electrons DROP DOWN in energy levels
the leftmost atomic emission band show the
GREATEST energy change
electromagnetic light in order of biggest to smallest wavelength
radio, micro, infared, UV, X-rays, gamma
