Key Autumn semester Flashcards
Equation for wave length
λv = c
λ Wavelength (m)
v frequency (Hz or s^-1)
c speed of light (2.998 x 10^8 m/s)
Equation for energy
E = hv
E energy (j)
h plancks (6.63 x 106-34 JS)
De Broglie relationship
Energies calculated for a wave and for a particle must be equal for anything behaving as both it shows wave-particle duality
λ = h/p
p momentum of particle (mass x velocity)
Uncertainty principle
You can not know both the position and speed of an electron but can estimate the probability that an electron is in a certain place
Heisebery uncertainty
The more we know the position of the electron the less we know about the momentum
ΔpΔx ≥ h / 4π
Δpx = mass x velocity
Δx = mass
Schrodinger equation
Tells use the likelihood of finding an electron an a particular location and the allowed wave functions
Quantum numbers and allowed values
n (principle quantum number) = which orbital the electron is located (1,2,3,4,5…)
l (orbital angular momentum) = shape of the orbital (0 to (n-1) ) 0 = S, 1 = p, 2 = d and 3 = f
ml (angular quantum number) = orientation of orbital (-l to +l)
Radial wave function
The probability of finding an electron in a spherical shell as r form the nucleus.
Found using n and small chance of finding e- far from the nucleus
Angular wave funtion
Shows the shape and orientation of orbitals
Electronegativity
The ability of an atomic nuclei to attract electron density shown by the Pauline scale
Lewis structures
Shows the connectivity and formal charges on atom in a structure
Resonance
The blending of two or more lewis structures, where the electrons are delocalised resulting in a resonance hybrid which is a lower energy
VSEPR
Valence shell electron pair repulsion which is used to determent he 3d structure of a molecule.
Lone pairs
Located closer to the central atom so has increased repulsion and so counted as a region of electron density and lower bonds angles
Dispersion forces
exist for all molecules and increase with an increase of electron, same as instantaneous induced dipole
Symmetry operation
An action that transforms a molecule so the resultant molecule is complete unchanged
Rotation
this is a rotation around a specific axis given as Cn for a rotation 1/n
C2 = 180 degree rotation (1/2)
C3 = 120 degree rotation (1/3)
C4 = 90 degree rotation (1/4)
C6 = 60 degree rotation (1/6)
Inversion
Centre of inversion (i) If any point of the molecule passes through a centre of inversion an dit remains the same
reflection
When reflection (σ) on a mirror plane either vertical or horizontal leave the molecule exactly the same
rotation-reflection
Sn > Rotating a molecule by Cn around an axis then reflecting it onto a place perpendicular to the same axis