Midterm 1 Flashcards
How can you thing of electromagnetic energy
imagine self-propagating transverse oscillating waves of electric and magnetic fields
how fast does electromagnetic radiation travel
the speed of light c = 299,792,458 ms
what are the 3 characteristics of waves
- frequency, V, how many peaks pass a point per second
- Wavelength, (lambda)
- amplitude (height from centre to top
how do you calculate the frequency or wavelength of an electromagnetic wave when you know the other
Frequency x wavelength = speed = 299,792,458
what are the possible levels for n = 1
n = 1
l = 0
ml =0
what are the possible levels for n = 2
n = 2
l = 0: nl=0
l = 1: nl = -1, nl = 0, nl = 1
what are the levels for n = 3
n = 3
l = 0: ml = 0
l = 1: ml = -1, ml = 0, ml = 1
l = 2: ml = -2, ml = -1, ml = 0, ml = 1, ml = 2
what do n, I,, and ml letters mean for orbitals
n = orbital level
l = suborbital (0=s, 1=p, 2=d, 3=f)
ml = different suborbital modes
what are p orbitals like
- dumbbell-shaped, have an angular node passing through the nucleus
- 3 variations, x, y, z
- all p orbitals have 1 angular node all other nodes are radial
what are d orbitals like
- 2 angular nodes
- 5 different orbitals within it due to ml values
- can have nodal cones (looks like a shaved ice cone)
what is electron spin
electrons behave like a very small bar magnet, so the direction they spin has effects
ms = spin angular momentum quantum number
= +/- 1/2
what are the possible spins for electrons
Spin up = +1/2, spin down = -1/2
these are show with up or down single sided arrows
what is Paull’s exclusion principle
- no 2 electrons can have the same set of four quantum numbers
- therefor 2 electrons in the same orbital must have opposite spins
what is the order of energy in orbitals and suborbital
- s<p<d<f: electron-electron repulsion causes energy of orbitals to increase within a shell in that order
- orbital size increases with n as does energy
summarize the rules for electron orbitals
n = integer > 1
l = integer between 0 and n-1
ml = integer between - l and + l
ms = +/- 1/2
every orbital has n-1 nodes
what is electron configuration
how electrons are distributed
what is ground state
the most stable configuration or ground state is that which the electrons are in the lowest energy state
what are the rules for writing electron configuration
when writing e- configuration
- fill orbitals in order of increasing energy
- no two electrons can fill the same orbital with same spin
what is Hund’s rule
for degenerate orbitals, the lowest energy is attained when the number of electrons with the same spin is maximized
what does Hund’s rule mean
means to spread out electrons in the p orbital, then fill with second electrons
they fill each orbital singly with their spins parallel before any orbital gets a 2nd electron (though this can be effected by artificial means
what is condensed electron configuration
electron configuration may be written in shorthand by turning the core electrons into their corresponding noble gas. (the inner shells don’t affect chemistry much)
then the valence electrons are written explicitly
(valence shell = outer shell where electrons are gained or lost in reactions)
ex:
Na 1s2 2s2 2p6 3s1 → Na [Ne]3s1
how does the periodic table relate to orbitals and sub orbitals
- the period # is the value of n for the s orbital
- s-block elements = Alkali + Alkaline earth, they only have s orbitals
- p-block = group 13-18 (except He) have p orbitals being filled
- d-block group = transition metals filling in d orbital
- F-block = lanthanids + actinides, filling f block orbitals
what are some anomalies within electron configuration
- Cr is [Ar]3d5 4s1 not [Ar]3d4 4s2
- Cu is [Ar]3d10 4s1 not [Ar] 3d9 4s2
this is due to the stability of half-filled and filled shell configurations
when atomic numbers are above 40 energy differences are small enough that anomalies occur
summarize the rules for electron configuration
- lower energy orbitals fill with electrons first
- any orbital can hold up to 2 electrons
- if 2+ degenerate orbitals are available, one electron goes into each orbital till all are half full, then the new electrons start filling the orbits
- A particularly stable configuration is one where a set of p or d orbitals is either filled or half filled