Last Minute Cram - Inorganic Flashcards
what can the em radiation be described as?
a wave and particle - dual nature
equations for em spectrum
c=fλ
E=hf
E=Lhc/λ
order of em spectrum (low f to high f)
radio microwave infrared visible ultraviolet x-ray gamma
what can emission and absorption spectra be used for?
to identify and quantify the element
atomic absorption spectroscopy
em radiation directed at an atomised sample
radiation absorbed as electrons are promoted to higher energy levels
absorption spectrum produced by measuring how the intensity of absorbed light varies with wavelength
atomic emission spectroscopy
high temperatures used to excite electrons to higher energy levels
as electrons drop to lower energy levels, photons are emitted
an emission spectrum of a sample is produced by measuring the intensity of light emitted at different wavelengths
what is the concentration of an element within a sample related to?
the intensity of light emitted or absorbed
lyman series
electrons dropping to the ground state
balmer series
electrons dropping to n=2
as energy increases…
levels get closer together and converge
what does the line of greatest energy represent?
electrons returning from the outermost shell to the ground state
if slightly more energy than the line of greatest energy?
electron removed
i.e. 1st ionisation energy
how to calculate ionisation energy
use the convergence limit in E=lhc/λ
principle quantum number
indicates the main energy level for an electron and is related to the size of the orbital
nearest nucleus n=1 and so on…
angular quantum number
determines the shape of the subshell and has values from zero to n-1 l=0 s orbital l=1 p l=2 d l=3 f
magnetic quantum number
determines the orientation of the orbital and has values between -l and l
use px,py and pz
3 possible p orbitals: -1,0,+1
5 d
7f
spin magnetic quantum number
determines the direction of the spin and can have values of +1/2 or -1/2
clockwise or anti-clockwise
orbital
region of space with a 90% probability of finding an electron
s orbital
spherical
diameter increases as shell no. increases
the only orbital in shell 1
p orbital
dumb-bell shaped
only occur from second shell onwards
all have equal energy - degenerate
each p orbtial can hold 2 electrons (px+py+pz=6)
maximum number of electrons in a single orbital
2
d orbitals
each shell from the third shell contains 5 d-orbitals
orientation: between x and y axis (dxy) between x and z axis (dxz) between y and z axis (dyz) along x and y axis (dx^2-y^2) along z axis (dz^2)
aufban diagram
orbitals ranked in terms of energy
the third and fourth shells overlap with electrons occupying the 4s orbital before the 3d one
aufbau principle
electrons will fill orbitals in order of increasing energy
Hund’s rule
for degenerate orbitals, electrons fill each orbital singly before pairing starts
pauli exclusion principle
maximum number of electrons in any atomic orbital is two and if there are two electrons in the same orbital, they must have opposite spins (no 2 electron can have the same quantum numbers)
ionisation energy across a period
in general, 1st IE increases across a period
exception: 1st IE of Boron is lower than Berylium
explanation: Berylium has a full sub-shell which is a stable arrangement
Boron has a single 2p electron which is less stable and easier to remove
special stability with half-filled and full subshells
isoelectronic
particles which have the same electronic configuration
unusual electronic configurations
chromium
2,8,13,1
1s2 2s2 2p6 3s2 3p6 3d5 4s1 instead of 3d44s2
stability of filled and half-filled orbitals
one electron in each d-orbital
symmetry around the nucleus
copper
2,8,18,1
1s2 2s2 2p6 3s2 3p6 3d10 4s1 instead of 3d9 4s2
symmetry around nucleus
order of orbital filling
note: always write in order of principal quantum number with accompanying s.p.d.f
1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p
ground state
electrons in lowest possible energy level
how is the periodic table divided into 4 blocks
depending on which subshell the highest energy electrons are found in
s block - group 1 and 2 (and He)
p block - groups 3-7
d block - transition metals
f block - lanthanide and actinide series