Chem chapter 6 Flashcards
Waves
disturbance that transmits energy through space
frequency (v)
the number of waves passing a point in a given amount of time
longer the wavelength
lower the frequency
speed of light
2.998x10^8 m/s
wavelength (λ) measured in
meters (m)
speed (c) measured in
meters per second (m/s)
frequency (v) measured in
hertz (Hz) or inverse seconds (s^-1)
equation for speed
c = v x λ
mnemonic for electromagnetic spectrum order
Red Men Interview Very Ugly Xylophone Guys
order for EM spectrum from longest wavelength to shortest wavelength
radio waves, radio waves, microwaves, infrared (ROYGBIV), ultraviolet, x-rays, gamma rays
constructive interference
when similar waves combine to form a larger wave
destructive interference
when unlike waves combine to get no wave (flat line)
diffraction
change in direction of waves as they pass through an opening or around a barrier in their path
refraction
bending of waves as they pass from one medium to another (think of a wave hitting water)
light has a ___ nature
dual wave-matter
photon
particle of light
what was wrong with classical (Newtonian) physics?
they could not get their experimental data to agree with theory, so they had to change the theory to fit the data
what three main issues caused a change in classical physics
blackbody radiation, photoelectric effect, and atomic emission spectra
blackbody radiation
energy is like matter, it is discontinuous or quantized
-the energy of a quantum of EM radiation is proportional to the frequency of the radiation
planks constant (h)
h = 6.626 x 106-34 Js
energy formula
E = hv
photoelectric effect
when light strikes the surface of certain metals, electrons are ejected
-emission only occurs at certain threshold frequencies (v_0)
E of photon equals
hv
atomic emission spectra
when an electron is struck with energy, the electron is excited, which causes it to emit light
blackbody radiation and the photoelectric effect suggest that
electrons could only occupy certain energy levels
Neils Bohr new model of atom
-electrons move around the nucleus in one fixed set of circular orbits (like planets around the sun)
-as long as the electron remains in a given orbit, no energy is emitted; fixed radius and energy
-an atom emits energy as a photon when the electron falls to an orbit with a smaller radius and lower energy
when an electron falls from a high energy level to a low energy level
it emits energy in the form of a photon (-)
when an electron goes from a low energy level to a high one
it can only do so if it absorbs photons (+)
energy levels
the allowed energy states of an atom
lowest energy level
ground state
n=1
excited state
when an electron moves out of the ground state into a state with a higher n value
delta E=
-2.18 x 10^-18 ((1/nf^2)-(1/ni^2))
ionization happens when
an electron leaves an atom entirely, resulting in an ion
-the energy this requires in hydrogen is the Rydberg constant
for hydrogen-like atoms, energy increases so the
atomic number (Z) also increases
increasing Z results in
-a greater charge
-affects the separation between the electron and the nucleus
what’s the equation between mass and wavelength
λ = h/p = h/mv
uncertainty principle
you can never determine the position AND momentum of an electron (you know one or the other)
principle quantum number (n)
related to the energy and probable distance of the electron from the nucleus; describing the SHELL where the electron is located
electrons with the same value of n are in
the same principal electron shell or level
n can have ____ number values
positive, non-zero, whole-number values
- n= 1, 2, 3, 4…..
angular momentum quantum number (l)
describes the shape of the orbital where the electron is located; describes the SUBSHELL where the electrons are
-all electrons with the same value of n and l are in the same subshell/sublevel
l can have ____ number values
positive, whole-number values (including zero_ but cannot be greater than the n value
- l= 0, 1, 2, 3 ,4…..
the number of subshells in a principal electronic shell is equal to
the number of possible l values
letters for the subshells for the first four values of l
l=0–>s
l=1—>p
l=2—>d
l=3—>f
magnetic quantum number (m sub l)
describes the orientation of the orbital where the electron is located
m_l can have ____ number values
negative or positive whole number values (including zero), ranging from the - to + l values
- M_l= -l…-2, -1, 0, 1, 2…+l
spin quantum number (m sub s)
describes the orientation of the electron spin
-can only have +/- 1/2
orbitals
the areas around the nucleus in which an electron is likely to be found
-The number of orbitals in a subshell is equal to the number of allowed m_l values for that subshell (2l+1)
s orbital shape (l=0)
spherical
p orbital shape (l=1)
two lobes with a node in the middle where electrons cannot go
d orbitals (l=2)
have multiple lobes and nodes
