atomic structure Flashcards
e (unit of charge)`
1.6E-19
atomic mass unit (amu)`
PROTONS have an atomic mass of one of these
atomic # (Z)
equal to the number of protons found in an atom of that element
the number on top of the element on the periodic table
mass # (A)
atomic mass
sum of the protons and the neutrons in the atoms nuc
isotopes
atoms that share an atomic #, but diff mass #, written as (^A vZ) X
atomic wieght
weighted average of the elements different isotopes and is reported below the element of the periodic table
Avogadro’s number, NA
6.02E23 molecules/mol
quanta
discrete bundles in which energy emitted as electromagnetic radiation from matter comes in
the energy of a quantum, given by PLANCK RELATION
E=hf
h- plancks constant 6.626E-34
f- frequency of the radiation
plancks constant, h
6.626E-34 Js
angular momentum equation
L=mvr
genetic energy equation
K=(0.5) m(v^2)
angular momentum of an electron orbiting a hydrogen nucleus
L=(nh)/(2 (pi))
n- principle quantum number (the electron shell #)
h- plancks constant 6.626E-34 Js
energy of the electron
E= -(RH)/(n^2)
RH- Rydberg unit of energy= 2.18E-18 J/electron
n- principle quantum number (the electron shell #)
RH
Rydberg unit of energy
2.18E-18 J/electron
excited state
when at least one electron has moved to a sub shell of higher than normal energy
photons
discrete amount of every that are emitted when electrons return rapidly o the ground state since the lifetime of an excited state is brief
electromagnetic energy of photons
E= (hc)/(λ)
h- plancks constant 6.626E-34 Js
c- speed of light in a vacuum- 3E8 m/s
λ - wavelength of the radiation
its just a combo of E=hf and c=fλ
speed of light in a vacuum (c)
3E8 m/s
line spectrum
each line on the emission spectrum corresponds to a specific electron transition
atomic emission spectrum
each element has this, and it can be used as a fingerprint for the elemnt
Lyman series
the group of H emission lines corresponding to transition from energy level n>=2 to n=1
includes larger energy transitions than the Balmer series, so it has shorter photon wavelengths in th eUV region of the electromagnetic spectrum
Balmer series
the group corresponding to transition f from energy levels n>=3 to n=2
Paschen series
corresponds tot transitions form n>=4 to n=3
E=hc/λ = -(RH) ( (1/ni^2) -(1/nf^2) )
this is a combo of Bohn and Planks calcs, and it really only says
the energy fo the emitted photon corresponds to the difference in energy btwn the higher energy initial state and the lower energy final state
absorption spectrum
unique to each element
wavelengths on this spectrum correspond exactly to the wavelengths of emssion
orbitals
regions of space around the nucleus in which electrons are localized and where they move rapidly
Heisenberg uncertainty principle
it is impossible to simultaneously determine, with perfect accuracy, the momentum and the position of an electron
modern atomic theory
postulates that nay electron in an atom can be completely described by 4 quantum #s: n, l, ml, and ms
Pauli exclusion principle
no two electrons in a given atom can posses the same set of four quantum numbers
energy state of an electron
position and energy of an electron described by its quantum numbers
quantum #s
n, l, ml, and ms
give info act the size, shape, and orientation fo the orbitals
principle quantum #
n
any positive integer vale
the larger the value of n, the higher the energy level and radium of the electrons shell
max # of electrons within a shell: 2n^2
azimuthal quantum #
l (L)
azimuthal (angular momentum) quantum #
refers to the shape and number of subshells within a given principle energy lvl (shell)
value of n limits value of l: for any given value of n, th orang elf possible value for l is 0 to (n-1)
spectroscopic notations
refers to the shorthand representation fo the principal and azimuthal numbers
s, p, d, f
l=0=s
l=1=p
l=2=d
l=3=f
max # of electrons within a subshel= 4l+2
magnetic quantum number
ml
specifies the particular orbital within the sub shell where an electron is most likely to be found at a given moment in time
possible values between -l and +l
spin quantum number
ms
the electron has two pain orientations, designated + 1/2 and -1/2.
if two electrons are in the same orbitals, they must have opposite spins, so they are paired.
electrons in diff orbitals with the same ms values are said to have parallel spins
electron configuration
use spectroscopic notation, where in the first number denotes the principal energy level, the letter designates the sub shell and the superscript gives th number of electrons in that sub shell
ex: 2p^4
Aufbau principle AKA building up principle
electrons fill form lower to higher energy subshells and each subshell will fill completely before electrons begin to enter the next one
n + l rule
can be used to rank subshells by increasing energy
the lower the sum of the values of n + l, the lower the energy of the subshell
if two subshells posses the same n + l value, the sub shell with the lower n value has a lower energy and will fill the electrons first
Hunds rule
within a given sub shell, orbitals are filled such that there are a maximum number of half filled orbital with parallel spins
paramagnetic
materials composed of atoms with unpair electrons will orient their spins in alignment with a magnetic field, and the material will thus be deadly attracted to the magnetic field
diamagnetic
materials consisting of atoms that have only paired electrons will be slightly repelled by a magnetic field
