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1

frequency

peaks per second in hertz (Hz) or s^-1... variable is v

2

speed of light

assuming a vacuum for this course... variable is c

3

wavelength

length from peak/trough of wave. can be nanometers or meters for units (use 10^9/10^-9 as conversion)

4

Electromagnetic Radiation Spectrum

shorter wavelength, higher frequency, higher energy

5

c= v(lambda)

inversely proportional
c= speed of light constant
v= frequency (waves per second)
lambda= wavelength
- don't forget to convert wavelength to match units of light

6

energy levels

are called shells, orbits or symbolized by "n". lower orbitals have less energy ex (n= 1 has less energy than n=4)

7

distance between energy levels

- energy levels get closer together the further you go

8

electron goes down an orbital

- electron loses energy so it will emit light of wavelength equal to energy lost

9

electron goes up an orbital

electron absorbs energy equal to wavelength of light given to it

10

absorption

electron goes up shell due to energy given to it

11

emission

electron goes down shell due to energy emitted

12

continuous spectrum of light (line spectrum)

shows rainbow
- all wavelengths on spectrum are visible light

13

emission lines (line spectrum)

few colours on a black backdrop visually
- the colours are wavelengths of light emitted when a gas atom was originally excited but that then electron emits the light was it goes back to rest state

14

absorption (line spectrum)

while light is going through a gas sample of an element, the electron would absorb some energy of that light causing

15

at what speed does all electromagnetic radiation move at?

the speed of light

16

electromagnetic radiation and energy transfer

ex. when molecules absorb radiation, it increases the energy of the molecules causing more collisions and a rise in temperature (case of microwave at least)

17

planck's quantum theory

energy can only be gained or lost in whole number multiples of hv where h is a constant. can find energy absorbed or released

18

quantum

small packet of energy that can only occur in discrete units. system can only transfer energy in whole quanta thus energy seems to have particulate properties.

19

photosns

einstein discovered that electromagnetic radiation can be seen as a stream of particles called photons

20

delta e=nhv OR delta e=hc/(lambda)

gives the amount of a single quantum (the energy of a photon of light)

n= an integer
h= planck's constant
v= frequency

21

dual nature of light

electromagnetic radiation can show certain characteristics of particulate matter which is called dual nature

22

de Broglie's equation

lambda= h/mv

23

lambda= h/mv

used to calculate the wavelength for a particle
- h=planck's constant
m= mass
v= AHAH it is velocity

24

1 joule equals

1 kg times m^2 / s^2

25

hydrogen emission line spectrum

shows that only certain energies are allowed for the electron in the hydrogen atom AKA the energy of the electron in hydrogen is quantized. changes in energy between discrete energy levels in hydrogen will produce only certain wavelengths of emitted light. if any energy level was allowed, the emission spectrum would be continuous

26

emission spectrum

emission: when hydrogen molecules absorb energy and some of the bonds are broken. this results in excitation of electrons which means they contain excess energy which they release by emitting light of various wavelengths to produce the emission spectrum

contains black but with some colour bars in between

27

if energy levels in atoms were not quantized

all light would be white (contains all wavelengths)

28

delta e= -2.178 times 10^-18 J times z^2 (1/n^2f-1/n^2i)

n= integer. larger n is larger orbit radius
z= atomic number (usually 1 for hydrogen)
f= final
i= initial

this is negative when there is emission

29

e= -2.178 times 10^-18 J times (z^2/n^2)

gives the energy of each energy level

30

n=6 to n=1

n=1 has more negative energy because the electron in that level is more tightly bound to the smallest allowed orbit. the change in energy then is negative as energy is lost and electron is now in a more stable state. the energy is carried away from the atom by the production (emission) of a photon