Chapter 7 Flashcards
Wavelength
distance between two consecutive peaks or troughs in a wave
Symbol for wavelength
λ
Frequency
number of waves that pass a given point per second
Energy is _______ and can occur only in discrete units of size called _______
quantized, hv
discrete units of size
hv
quantum
the smallest amount of energy
electrons can be viewed as a stream of “particles” called?
photons
phenomenon in which electrons are emitted from the surface of a metal when light strikes it
photoelectric effect
when are electrons emitted from the surface of a metal?
when light strikes it
when electromagnetic radiation exhibits wave properties and particulate properties is a phenomenon called?
dual nature of light
diffraction
when light is scattered from a regular array of points or lines
diffraction pattern
bright spots and dark areas on a photographic plate
when does a diffraction pattern occur?
scattered light interfere constructively to produce a bright area or destructively to produce a dark area.
interfere constructively
the peaks and troughs are in phase
interfere destructively
the peaks and troughs are out of phase
continuous spectrum results when?
white light is passed through a prism.
the energy of the electron is?
quantized
quantized
to subdivide energy into very small but measurable increments
what is significant of the line spectrum of hydrogen?
indicates only certain energies are allowed for the electron
what is the quantum model?
the electron in a hydrogen atom moves around the nucleus only in certain allowed circular orbitals
A hydrogen atom in its lowest possible energy state is called?
ground state
the electron bound to the nucleus is similar to?
standing wave
orbital
a specific wave function
Heisenberg uncertainty principle
there is a limitation to just how precisely we know the position and momentum of a particle at any time.
Probability distribution
the probability of finding the electron at points along a line drawn outwards from the nucleus.
frequency symbol
v
why do we see visible light?
the chemical reaction that takes place within our retina
how does all types of electromagnetic radiation travel?
at the speed of light
short waves have a ____ frequency
high
what is wavelength measured in?
meters
what is frequency measured in?
Hz (hertz)
symbol for speed?
c
symbol for planck’s constant?
h
long wavelengths have _____ frequencies.
low
Max Planck postulated what?
energy can be gained or lost only in whole number multiples of the quantity hz
a system can transfer energy only in?
whole quanta
Einstein proposed that electromagnetic radiation is itself?
quantized
electromagnetic radiation
stream of photons traveling in a wave like pattern at the speed of light.
photon
stream of “particles” suggested by electromagnetic radiation
Important conclusions of Planck and Einstein
- Energy is quantized and can occur only in quanta
- Electromagnetic radiation shows characteristics of particulate matter and wave properties. (dual nature of light)
all matter exhibits both?
particulate and wave properties.
when H2 molecules absorb energy what happens to the bonds?
the bonds are broken resulting in excited atoms
what is produced when excess energy is released from hydrogen atoms?
An emission spectrum
Emission spectrum
a series of colored lines that correspond to wavelengths emitted by the glowing gas.
what colors does a continuous spectrum possess?
rainbow
Important points about the Bohr model (3)
-The model correctly fits the quantized energy levels of the hydrogen atom and only allows certain circular orbits for the electron
- As the electron becomes more tightly bound, its energy becomes more negative
- As the electron is brought closer to the nucleus, energy is released from the system
wave function
a function of the coordinates (x,y,z) of the electrons position in 3-D space
quantum wave mechanical model
the electron is able to move freely within its own home orbital and can gain energy and jump to a higher energy level
Pauli Exclusion Principle
In a given atom no two electrons can have the same set of four quantum numbers.
l=1
p
l=0
s
l=2
d
l=3
f
to Schrodinger and de Brigolie the electron bound to the nucleus seemed similar to?
standing wave
In the quantum mechanical model, Specific electron motions are?
unknown
In the quantum mechanical model, the specific electron motions help determine?
the most probable distance at which the electron is found
Principle Quantum number has ____ values?
integer
As n increases, what happens to the orbital and energy of the electron?
orbital becomes larger with more electrons away from nucleus. Energy is higher since electron less tightly bound to the nucleus.
angular momentum quantum number symbol
l
angular momentum quantum number has values from?
0 to n-1
the angular momentum quantum number is related to?
the shape of atomic orbitals
magnetic quantum number symbol
ml
the magnetic quantum number has integer values between
l and -l including zero
the value of ml is related to?
the orientation of the orbital in space
l is also called?
subshell
the number of nodes increases as?
n increases
node
area of zero probability if finding an electron
shape of the s orbital
spherical
shape of p orbitals
2 lobes separated by a node at the nucleus
electron spin quantum number symbol
ms
ms can only have two values?
+.5 and -.5
Since only 2 values of ms are allowed, an orbital?
can only hold two electrons and must have opposite spins
poly electronic atoms
atoms with more than one electron
3 energy contributions that must be considered of the description of poly electronic atoms?
-KE as move towards the nucleus
-PE of attraction btwn the nucleus & electrons
-PE of repulsion between 2 electrons
Electron correlation problem
since electron pathways are unknown, the electron repulsion cannot be calculated
electron repulsion
electrons staying as far apart from each other as possible due to their same charge
2s orbital is lower than a _____ orbital in poly electronic atoms
2p
the more effectively an orbital allows its electrons to penetrate the shielding electrons to be closer to the nuclear charge, what happens to the energy of the orbitals?
lowers
Aufbau principle
as protons are added one by one to the nucleus to build up elements, electrons are similarly added to the hydrogen-like orbitals
Hund’s rule
the lowest energy for an atom is one having the max number of unpaired electrons allowed in a particular set of degenerate orbitals
inner elements are known as?
core elements
elements on which the 4f orbitals are being filled
lanthanides
elements on which the 5f orbitals are being filled
actinides
Ionization energy
energy required to remove an electron from a gaseous ion or atom in gorund state
In the process of ionization ______ energy electrons are removed first.
highest
first ionization energy
energy required to remove the highest energy electron of an atom
Second ionization energy
energy required to remove the highest energy electron of an ion
trend in ionization across a period
increase
why does ionization energy increase across a period?
due to increasing nuclear charge which results in electrons being more strongly bound to the nucleus
trend in ionization down a group
decrease
why does ionization decrease down a group?
due to the outermost electron being father from the nucleus
atomic radius
the measure of size of an element
trend in atomic radius across a period
decrease
why does atomic radius decrease across a period
due to the increase in protons the nuclear charge attracts the electrons more strongly.
trend in atomic radius down a group
increase
why does atomic radius increase down a group?
the number of energy levels increases so there is a greater distance between the nucleus and outermost orbital
group 1A
alkali
group 2A
alkaline earth metals
group 7A
halogens
group 8A
noble gases
metals tend to _____ electrons and form _____.
lose, cations
metals tend to have ______ ionization energies
low
where are most active metals located on the table?
bottom left corner
nonmetals tend to ____ electrons and form ____.
gain, anions
electron shielding
the blocking of valence shell electron attraction by the nucleus, due to the presence of inner-shell electrons.
