CHEM 111 3.1-3.5 (start to 3.6-3.7)

Vocab from 9/4 Lecture Notes

wavelength

distance between 2 consecutive peaks/troughs in a wave (meters)

• shorter wave = higher frequency

frequency

number of successive wavelengths that pass a given point in a unit time (Hz or s^-1)

amplitude

½ the distance between the peaks + troughs

speed (C)

C = wavelength x frequency

constructive interference

maxima from both waves coincide

destructive interference

one maximum coincides with/ another minimum

photons

particles of light

E = hv

Plank’s constant (h)

relates energy of photon to its frequency

• higher frequency = higher photon NRG

• J x s

what does a line spectra show?

• emission of light at wavelength SPECIFIC for a given atom

• (electrical charge excites atom —> light is emitted)

wave-particle duality

light behaves both as a particle and a wave

• so do other small particles (electrons + neutrons)

Heisenberg Uncertainty Principle

small particles moving fast do not have a definite position/speed

angular momentum quantum (ℓ)

• integer that defines shape of the orbital

• ℓ = n-1

magnetic quantum number (m)

• specifies orientation of the orbital space

spin quantum number (m_s)

• describes 2 possible states

radial nodes

• area around an atom’s nucleus where the chance of finding an e- is 0

• e- wave function (ψ) = 0 at this instance

• # radial nodes in an orbital = n - ℓ - 1

e- orbitals

shielding

• e- in smaller orbitals/ closer to the nucleus = core e-

  • ex: 1s, then 2s + 2p

• core e- shield outer e- from some nuclear charge

Pauli Exclusion Principle

• no 2 e- in the same atom can have the same set of all 4 quantum #s

bc. . .

• 1 orbital holds 2 e- max

• e- in the same orbital must have opposite spin

Aufbau Principle

• lowest NRG orbitals are filled first

Hund’s Rule

• e- want parallel spin in the same energy level/orbital w/o a being paired

• e- only pair w/ opp spin when the lower orbital is full

valence e-

e- occupying the orbital in the outermost shell (largest n value)

core e-

e- occupying the inner most shell (lowest n level)

anion

• - charged ion

• forms when 1 or more e- are ADDED to an atom

• larger than atom of same element at ground state

cation

• + charged ion

• forms when 1 or more e- are REMOVED from an atom

• smaller than atom of same element at ground state

isoelectronic

atoms w/ same e- configuration

• ex: N^3-, O^2- : (1s²2s²2p⁶)

• in this case Z determines size (greater nuclear charge = smaller radius)

1st Ionization NRG (IE₁)

• amount of NRG required to remove the outermost e- from an atom in ground state

IE₂

• NRG required to remove the 2nd outermost e-