Exam 1 Part 1

Question 1

Describe the wavelength, energy, and frequency of red light.

Answer 1

long wavelength
low energy
low frequency

Question 2

Describe the wavelength and frequency of UV light.

Answer 2

Short wave length
high energy
high frequency

Question 3

What is the Photoelectric effect?

Answer 3

When light hits the surface of metal, particles are ejected, and electrons are emitted

Question 4

Where do the electrons come from in the Photoelectric effect?

Answer 4

They come from the metal which contains atoms -> electons

Question 5

How much energy do electrons leave with in the Photoelectric effect?

Answer 5

It depends on the wavelength of the light

Question 6

Do metals like to lose electrons and why?

Answer 6

No, it takes energy (lowers potential energy)
they only have a finite amount of energy

Question 7

What is the relationship between E_light and wavelength?

Answer 7

E_light is inversely proportional to wavelength (1/lambda)

Question 8

What is the relationship between E_light and frequency

Answer 8

E_light and frequency are directly proportional

Question 9

What does v stand for?

Answer 9

frequency

Question 10

What does lambda stand for?

Answer 10

wavelength

Question 11

What is the relationship between E_light and intensity?

Answer 11

E_light and intensity are directly proportional

Question 12

What is another word for intensity?

Answer 12

brightness

Question 13

What does psi stand for?

Answer 13

work function (constant)

Question 14

What does the atomic number tell you?

Answer 14

protons=electrons

Question 15

Explain why the photoelectric effect SHOULD “work” if intensity is high enough?

Answer 15

Intensity is proportional to energy (E_light)
so it should have overcome the threshold
E_light> Psi

Question 16

Explain why the photoelectric effect DOESNT ALWAYS “work” if intensity is high enough?

Answer 16

only get potential energy iff the frequency is greater than initial frequency
v>v_o

Question 17

Explain the expectation that KE should increase with intensity.

Answer 17

Intensity is proportional to E_light and
KE_e-=E_light-

Question 18

What is intensity represented by on a wave function graph?

Answer 18

amplitude (middle of the graph to ‘hump’

Question 19

Is light one big wave or a bunch of small waves?

Answer 19

a bunch of small waves (photons)

Question 20

What does the color of a light determine?

Answer 20

The wavelength

Question 21

Describe the relationship between photons and brightness.

Answer 21

of photons increase

as brightness increases
#photons increases

Question 22

What are photons?

Answer 22

The smallest ‘piece’ of light and the smallest unit of energy for a given wavelength

Question 23

Explain the photoelectric effect in terms of photons.

Answer 23

The atom of the metal needs enough photons to get e- to leave

Question 24

What does the variable h stand for?

Answer 24

planks constant

Question 25

What does the variable c stand for?

Answer 25

the speed of light

Question 26

What is the definition of brightness?

Answer 26

change in # of photons

Question 27

What is absorption?

Answer 27

Electron in atom gains energy

Question 28

What is emission?

Answer 28

Electron in atom releases energy

Question 29

Is the system happier at ground state or excited state?

Answer 29

The system is happier at ground state because it has a lower energy (delta H)

Question 30

In an energy level diagram, would a red light be the small energy level jump or the largest?

Answer 30

smallest because energy is inverse to wavelength

Question 31

Describe the Bohr Model for H-atom?

Answer 31

tiny e- orbits massive proton
imposed quantized energy levels on electron in atom
leads to quantized orbital radii
predicts locations of spectral lines (lambda)

Question 32

What does the constant l stand for?

Answer 32

angular momentum

Question 33

Negative potential energy is ____.

Answer 33

Attraction

Question 34

Positive potential energy is ____.

Answer 34

repulsion

Question 35

In the Bohr Model: explain what happens to energy as n gets bigger.

Answer 35

As n gets bigger the energy gets closer to 0 and the energy level approaches infinity

Question 36

True/False: In the Borh Model: To move infinitely far away, it take infinite energy.

Answer 36

False, It takes a finite amount of energy to move infinitely far away

Question 37

Describe the ‘sign’ (+/-) of Energy at n=1 and what happens to it as n increases.

Answer 37

at n=1 Energy is the most negative and get less negative as n increases
energy approaches 0

Question 38

What did the Bohr Model not explain?

Answer 38

Variation in spectral line intensity (brightness)
Change in spectra (color) in presence of magnetic field
Spectra of atoms with 2 or more electrons**

Question 39

Explain the idea of light as it relates to Wave-Particle Duality.

Answer 39

It was classically thought of as a wave but now as a particle because it is individual photons

Question 40

Explain the idea of matter as it relates to Wave-Particle Duality.

Answer 40

Matter can appear as both a particle and a wave (has both properties)

Question 41

What does the constant p stand for?

Answer 41

momentum

Question 42

Who suggested there was wavelength for particles?

Answer 42

DeBroglie

Question 43

Explain the relationship between the size of things and their wavelength.

Answer 43

small things have noticeable wavelengths and large things do not