Atomic Structure Flashcards
proton
+1e or atomic mass unit (amu)
atomic number (Z)
number of protons found in an atom of an element
mass number (A)
sum of the protons and neutrons in an atom’s nucleus
isotopes
share an atomic number but have different mass numbers
electron
-1e; approximately 1/2000 the mass of a proton
shells
electrons in higher shells are further away from the nucleus and have higher energy
valence electrons
furthest from nucleus; most likely to become involved with other atoms
cation
positively charged atoms
anion
negatively charged atom
atomic mass
nearly equal to mass number
three isotopes of hydrogen
protium: one proton; deuterium: one proton and one neutron; tritium: one proton and two neutrons
atomic weight
weighted average of different isotopes; number found on periodic table
Avogrado’s number
a mole is a number of things equal to this number; 6.02E23
quanta
discrete bundles of of electromagnetic radiation emitted from matter
Planck Relation
the energy of a quantum; E=hf
h=Planck’s constant (6.626E-34 J*s)
f= frequency of radiation
possible values for angular momentum of an electron orbiting a hydrogen nucleus
L=nh/2pi
n= principal quantum number
h= Planck’s constant
possible energy of an electron
E=-R/n^2
R=Rydberg unit of energy, 2.18E-18 J/electron
n=principal quantum number
orbit
defined pathway in which an electron revolves at a discrete energy value
ground state
state of lowest energy of an atom; all electrons are in the lowest possible orbitals
excited state
when at least one electron has moved to a sub shell of higher than normal energy
photon
discrete amount of energy released when an atom goes from an excited state back to ground
equation to find electromagnetic energy of a photon
E=hc/gamma
h= Planck’s constant
c= speed of light in a vacuum (3.0E8)
gamma= wavelength of radiation
line spectrum
each line on the emission spectrum corresponds to a specific electron transition
atomic emission spectrum
a unique spectrum that outlines the set of distinct energy levels that an element’s electrons can be excited to
Lyman series
group of hydrogen emission lines corresponding to transitions from energy levels n>2 to n=1
Balmer series
group of hydrogen emission lines corresponding to transitions from energy levels n>3 to n=2
Paschen series
group of hydrogen emission lines corresponding to transitions from energy levels n>4 to n=3
Energy of electron transition
E= -Rh(1/(Ni^2)-1/(Nf^2)); the energy of the emitted photon corresponds to the difference in energy between the initial state the lower-energy final state
absorption spectrum
unique spectrum outlining the distinct energy levels that an element’s electrons must absorb to transition to a higher level
orbital
localized region of space within which electrons move rapidly
Heisenberg uncertainty principle
it is impossible to simultaneously determine, with perfect accuracy, the momentum and the position of an electron
Pauli exclusion principle
no two electrons in a given atom can possess the same set of four quantum numbers
principal quantum number (n)
the larger the n, the higher the energy level and radius of the electron shell
maximum number of electrons in a shell
2n^2, where n is the principal quantum number
azimuthal (angular momentum) number, l
- refers to the shape of the subshells within a given principal energy level
- possible numbers for l are from 0 to (n-1)
spectroscopic notation
shorthand representation of the principal and azimuthal quantum numbers l=0 subshell: s l=1 subshell: p l=2 subshell: d l=3 subshell: f
maximum number of electrons within a subshell
4l+2
magnetic quantum number, ml
- specifics the particular orbital within a subshell where an electron is most likely to be found
- possible values for ml are the integers between -l and +l
orbital shapes
s orbital- spherical shape
p orbital- dumbell shaped
spin quantum number, ms
electrons have two spin orientations: +1/2 or -1/2
paired spins
electrons with opposite spins; electrons in the same orbital must be paired
parallel spins
same ms values; must be in different orbitals to be paired
electron configuration
determines the pattern by which subshells are filled as well as the number of electrons within each principal energy level and shell
Aufbau (building-up) principle
electrons fill from lower to to higher energy subshells; each sub shell will fill completely before electrons begin to enter the next one
n+l rule
used to rank subshells by increasing energy; the lower the sum of the values of the first and second quantum numbers, the lower the energy of the subshell; sub shell with lower n value will fill first
cation electron configuration
start with neutral atom, remove electrons from subshells with highest n value first
Hund’s rule
within a given subshell, orbitals are filled such that there are a maximum number of half-filled orbitals with parallel spins
paramagnetic
materials composed of atoms with unpaired electrons that orient their spins in alignment to a magnetic field
diamagnetic
materials consisting of only paired electrons are slightly repelled by magnetic field
