Chem-Atomic Structure Flashcards
(The nuclear model) previously, we have established that:
- atoms are composed of …, …, and …
- The protons and neutrons comprise almost all the atom’s … and are found in the very small ….
- The electrons are outside the … and occupy almost all the atom’s …
protons; neutrons; electrons; mass; nucleus; nucleus; volume
(The nuclear model) protons and neutrons are much … than electrons: almost … times heavier
protons and neutrons can be thought of as being … in the center of the atom, forming its “…”
The electron moves around so rapidly that its location is never certain. It forms an “…” around the nucleus.
heavier; 2000; stationary; nucleus; electron cloud
(The nuclear model) the volume of the parts of the atom are near … compared to the volume of the atom.
atoms are mostly …
zero; empty space
(The nuclear model) the … within atoms is what makes matter seem “…”
repulsion of the electron clouds; solid
(The nuclear model) since atoms are almost completely empty, there is nothing to keep the electrons and the nucleus apart. So why don’t atoms collapse?
Electrons don’t orbit the nucleus –> if this were true, electrons would constantly be …. as they orbit around the nucleus.
An accelerating charge radiates … in the form of ..
Atoms would constantly be emitting …
accelerating; energy; light; light
(The nuclear model) a charge radiating light loses … all the kinetic energy of the electron would be radiated away in about a billionth of a second. the electron would fall into the nucelus and all the atoms in the universe would collapse
energy
(The nuclear model) problems with the nuclear model:
1. atoms are … and they don’t …
if an atom’s electrons were continuously orbiting the nucleus they would radiate … and … in a billionth of a second
stable; collapse; energy; collapse
(The nuclear model) 2. atoms do not emit … mst of the time.
if an atom’s electrons were continuously orbiting the nucleus, they would radiate light …
light; continuously
(The nuclear model) 3. when atoms do emit energy, it consists of only specific …
most are absent, only narrow lines of color are observed
colors
(The nuclear model) a scientist named Niels Bohr interpreted these observations and created a new model of the atom that explained the existence of … and provided a framework for where the electrons can … around the nucleus
emission spectra; exist
(The nuclear model) bohr knew that the wavelengths seen in the light of hydrogen consisted of lines in … each series of lines were named for the … who created a model for it
regular patterns; scientist
(The nuclear model) each scientist created a formula which predicted a series of … emitted. These were defined by their….
the models used the variable … but no one knew what it represented
colors; wavelength; n
(the bohr model) bohr proposed that n defined … around the nucleus
electrons could orbit the nucleus, like planets orbit the sun, but only at … These increase in proportion to .., so orbits get much larger as n …
permitted electron orbits; permitted radii; n^2; increases
(the bohr model) he proposed that electrons would not radiate energy while travelling in a …
this violated the normal rules of .., since orbiting charges should radiate energy. But, Bohr proposed that, somehow, those rules would not apply to electrons in these orbits
permitted orbit; electromagnetism
(the bohr model) bohr proposed that electrons would … (or …) energy when they move between permitted orbitals.
each orbital represents a different …
the energy of the light emitted/absorbed is equal to the … in the starting and ending energy level of the electron
radiate; absorb; energy level; difference
(the bohr model) for each n, there is an … designated En.
The … of an atom is the lowest energy level when n = 1. We can call that energy level E1.
Then E2 will be the energy when n = 2 and so on
energy level; ground state
(the bohr model) At around the same time that the Bohr model was being developed, Einstein and the others developed a …
In this theory, light is emitted as a … particle called a …, each of which carries a specific amount of …
particle theory of light; massless; photon; energy
(the bohr model) the energy of a photon is given by this formula:
…
h is called …
f is …
E = hf; Planck’s constant; frequency in Hz
(the bohr model) for all waves: c = …
using this equation and the E= hf equation,
E = …
lamda*f;
hc/lamda
(the bohr model) All the lines in the hydrogen spectra were explained by …’s model.
The highest energy series, the … series, which is in the …, is due to transitions to the …, as shown here.
Bohr’s; Lyman; ultraviolet; ground state
(the bohr model) The next highest energy series, the .. series, which is in the … and the …, is due to transitions to the n = 2 energy level.
You can see that the energy released is smaller than in … to the ground state, so the frequency of the emitted light is lower, and the wavelength is longer.
ultraviolet; visible; transitions
the lowest energy series, the … series, is in the … and is due to transitions to the … energy level, as shwon here.
You can see that the energy released is smaller than in transitions to the ground state or to the n =2 level, so these are the lowest frequency …, with the longest wavelength
Paschen; infrared; n = 3; light
the spectrum of light being made up of lines of specific color is explained as being due to the … released when an electron moves to a …level
specific energy; lower energy
an electron can take a number of routes back to its ground state, released … in each step.
photons
due to the differing numbers of protons in the nucleus and the number of electrons around them, each atom produces a … after being energized.
unique emission spectrum
since the emission spectrum of each element is unique, it can be used to … the presence of a particular element
identify
the same energy that is released when an electron drops to a lower energy level, is required to take it up to …
when exposed to white light, the atoms absorb bands of light equal to the difference in …
the pattern for .. and .. spectra are the same
that level; energy level; absorption; emission
since electrons can only transition between orbits of …, atoms must absorb energy at the same frequencies at which they … We can use the spectra to identify elements or molecules.
set energies; emit energy
more electrons = more … lines
spectral
Bohr’s model answered a lot of questions but it still had some problems:
1. …. atoms did not have the energy levels predicted by the Bohr model
2. … and … bands appear in the emission spectra. the model does have an explanation for why some energy levels are very close together.
it takes … to provide a more accurate picture of the atom
multi-electron; double; triple; quantum mechanics
while a big step forward, Bohr’s model was only useful in predicting the frequency of spectral line for atoms that had one electron, like hydrogen or certain ionized atoms.
The idea that the electron was a particle in orbit around the nucleus, but with wavelike properties that only allowed certain orbits, worked only for hydrogen.
Semi-classical explanations failed expect for hydrogen. It turned out that only a lucky chance let it work even in that case.
significance of double slit experiment: shows … of matter
duality
quantum mechanics is a branch of physics which provides a mathematical description of …, and successfully explains the following 2 ideas:
1. the energy states in complex … and …
2. the relative brightness of …
it is widely accepted as being the fundamental theory underlying all physical processes
wave-particle duality; atoms; molecules; spectral lines
de Broglie proposed matter might also behave like a wave and have a wavelength associated with its … and …
He earned a Nobel Prize for a simple derivation of recent discoveries about energy and matter, setting Einstein’s formula relating energy and matter equal to … relating energy and frequency of a wave
momentum; mass; Planck’s formula
the de-broglie hypothesis that particles have wavelike properties needed to be supported by experiment. Davission and Germer of ell labs found that electrons could be … just like light waves
diffracted
the bohr model of the atom holds electrons in specific energy levels and locations around the nucleus of an atom. Quantum mechanics tells us there are inherent limits to measurement of the … and … of an electron aroun an atom. This is not because of the limits of our instruments, rather it is due to the .. and to the interaction between the observing equipment and the object being observed
position; momentum; wave-particle duality
try to find the position of an electron with a powerful microscope. at least one photon must scatter off the electron and enter the microscope. however, in doing so, it will transfer some of its … to the electron. electrons are so small that the very act of observing their position changes their position
momentum
what heisenberg postulated was that there is a limit to how accurately you can simultaneously know both the … and the … of the particle, no matter how good the measurement instrument. the more accurately you know the position of a article, the less likely you can describe its momentum and vice versa. the result of this uncertainty is to limit the outcomes of an experiment. for example, a quantum transition between two states of an atom always results in the emission of a photon of very specific energy
position; motion
simultaneous to heisenberg’s work, Schrodinger was working on a mathematical model that would describe the … of an … around an atom. treating the electron as a wave, Schrodinger’s wave equation descries the most probable position of an electron in terms of a … Erwin Schrodinger received the Nobel Prize in Physics in 1933 for the development of the Schrodinger Equation.
behavior; electron; wave function
the wave function (psi) describes the … and … of an electron. each wave frequency is proportional to the possible … of the oscillator. Each wave function is associated with a set of … which accurately describe the energy and most probable location of any electron of any atom
state; behavior; energy level; four quantum numbers
in classical physics, predictions about how objects respond to forces are based on … In quantum physics, this no longer works; predictions are based on …
Hpsi = Epsi
Where H is the …, E is the energy, and psi is the …
Newton’s Second Law; Schrodinger’s Wave Equation; Hamiltonian operator; wave function
since we cannot say exactly where an electron is, the Bohr picture of the atom, with its electrons in neat orbits, cannot be correct.
Quantum theory describes an electron …;
the probability of finding an electron somewhere is represented by the density of dots at that location.
probability distribution
solutions to Schrodinger’s wave equation take the form of sets of numbers. There are four different quantum numbers: …, …, …, … needed to specify the …. or probable … of an electron in an atom
n, l, ml, ms; state; location
n: … quantum number–> .. level/ … from the nucleus
l: .. quantum number –> … of orbital
ml: … quantum number–> … of orbital in space
ms: … quantum number–> direction of electron …
principal; energy; distance; angular; shape; magnetic; orientation; spin; spin
an orbital is a region of space where an electron is ….
the principal quantum number, n, describes the … of the orbital, often called the …
The values of n are integers greater than or equal to …
in general, the larger the value of n, the … from the nucleus the electron should be found
most likely to be found; energy level; energy shell; 1; farther
each orbital region or … has a very specific shape based on the … of the electrons occupying them and a specific orientation in space.
quantum number … designates the shape of the orbital. There are four shapes of orbitals: …, …, …. and …
quantum number .. designates the orientation of the orbital in space
subshell; energy; l; s; p; d; f; ml;
s orbitals are … in shape. the radius of the sphere … with the value of n.
if you are looking for an electron in an s orbital, the direction you look in doesn’t really matter, they have … orientation in space
spherical; increases; one
p orbitals have … with a .. between them.
For p orbitals, the electron density, and the probability of finding an electron, depends on both the … and the … from the center of an atom
two lobes; node; distance; direction
the p subshell has … possible arrangements in space, so it can have … possible orbitals
3; 3
d orbitals have more complex shapes. there are … possible orientations in space, so there are … possible d orbitals.
there are … possible f orbitals
5; 5; 7
in the 1920s, it was discovered that two electrons in the same orbital do not have exactly the same …,, which led to a fourth quantum number, the … quantum number
energy; spin
the spin of an electron describes its …, which affects its …
the spin quantum number can be … or ..
this implies that electrons are in some way able to pair up, even though they repel each other due to the ….
each orbital can therefore hold a max of … electrons
magnetic field; energy; positive; negative; electromagnetic force; 2 electrons
angular quantum number l = …
magnetic q.n. –> …
spin quantum = .. or ..
n - 1; -l >= ml <= l; +1/2; -1/2
as the number of electrons increases, so does the … between them. complex atoms contain more than one …, so the interaction … electrons must be accounted for in the energy levels. This means that the energy depends on both .. (…) and … (…)
repulsion; electron; between; n; the shell; l; the subshell
notice that some sublevels on a given n level may have … energy than sublevels on a lower n level
less
each box in an orbital diagram represents one …
orbitals on the same subshell are …
… represent the electrons
direction of the arrow represents the …
orbital; drawn together; arrows; relative spin
aufbau principle: electrons are added one at a time to the … available until all the electrons of the atoms have been accounted for
pauli exclusion principle: an orbital can hold a max of 2 electrons. to occupy the same orbital, two electrons must … in the …
hund’s rule: if two or more orbitals of equal energy are available, electrons will occupy them … before filling orbitals in ..
lowest energy level; spin; opposite direction; singly; pairs
pauli: no two electrons in the same atom can have the exact same …
quantum numbers
electron configurations show the … of all electrons in an atom. each component consists of:
- a number denoting the …
- a letter denoting the type of …
- a superscript denoting the number of … in those orbitals
distribution; shell; subshell; electrons
electron configurations are always written based on the energy level of the … not the …
the … configuration is that of a neutral atom
subshell; shell; ground-state
