Atomic Structure
Electromagnetic Radiation
• Energy traveling through space
c = λ* ν
• Wavelength – (λ) distance between 2 peaks or
troughs on a wave
– Units: m, cm, nm
• Frequency – (ν) # waves that pass a point in time
– Units: Hertz (Hz) or /s
• Speed of light – (c) = 3.0*108 m/s
Energy of photons
E = h*ν
or
E
ℎ∗𝑐
=
𝜆
E = energy
h = Planck’s constant = 6.626*10-34 J*s
Photons = particles of electromagnetic radiation
quantums = packets of energy
Also have E = mc2
can combine all
equations
Spectrums
• See light patterns
• Electromagnetic Spectrum – shows all types of
electromagnetic radiation
• Diffraction – light is separated (see colors of
rainbow from white light)
– See dark and light spots
• Continuous spectrum – see ranges or bands of
color
• Line spectrum – see only specific wavelengths
(looks like lines of color)
– Changes in energy emit certain colors
Bohr Model of Atom
• Primarily dealt with Hydrogen atom
• Also called Planetary Model
• electrons orbit the nucleus like the planets
orbit the sun
• Electrons reside in specific energy levels
– Lowest possible state = ground state (level 1)
– Higher states = excited states
– Absorb energy to go to excited state; emits
light/energy when comes back down
Quantum Mechanical Model of Atom
• Quantum Mechanics – deBroglie, Schrodinger,
Heisenberg
• Electrons not just particles – also act as waves
• Find electrons in orbitals – know probable location of
electron but not exact at any given time (Heisenberg
Uncertainty Principle)
• Schrodinger assigned quantum numbers to describe
properties of electrons
– Principal quantum number (n) = main energy level/shell
(n=1,2,3,….)
– Angular momentum quantum number (l) = shape =
block/subshell (s=0; p=1; d=2; f=3)
– Magnetic quantum number (ml) = orientation (-l to +l)
– Spin quantum number (ms) = +1/2 or -1/2
Orbital Shapes
s orbital = sphere - only 1 orientation (s)
have nodes – areas of high probability and 0 probability
p orbital = dumbbell shape – 3 possible
2 lobes oriented about x,y,z axes (px, py, pz)
d orbital = double dumbbell – 5 possible
4 lobes oriented about x,y,z axes (dxy, dyz, dxz, dx2y2, dz2)
f orbital = 3 dumbells – 7 possible
6 lobes oriented about x,y,z axes (fxyz, etc)
Pauli Exclusion Principle = no 2 electrons can
have the same set of quantum numbers
Example: Sulfur
Identify Group, Period, block, total # eWrite orbital notation/orbital diagrams to see
specific quantum numbers for atoms/electrons
lines/boxes with arrows (2 opposite arrows on each line)
(Aufbau Principle = building up)
• Electron configuration
– Show all electrons in the atom
• Noble Gas notation
– Short hand – bracket off number electrons equal
to previous Noble gas
• Remember d orbitals – 1 less than the period
they are in (3d in period 4); and f orbitals – 2
less than the period they are in (4f in period 6)
Periodic Table
• Arranged according to increasing atomic number
• Grouped according to similar properties or
characteristics
• Periodic Trends:
– Ionization energy
– Electron affinity
– Atomic radius
– Metallic character