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Atom Structure Flashcards

+ additional Physical flashcards

1
Q

The common theory is that light can act as a wave and as a particle. How was Einstein able to demonstrate the 2 different phenomena?

A

As light travels through a medium, it moves in a wave like manner, consisting of frequencies and amplitude.
When it enters an atom and interacts with electrons, it acts much like a particle (a photon interacting with an electron)

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2
Q

Of the following ions, which will have the smallest radius in a mass spectrometer?

A. Carbon - 12
B. Nitrogen - 14
C. Oxygen - 16
D. Potassium - 19

A

A. Carbon - 12 has the smallest mass

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3
Q

What is the basis of mass spectrometry? How does isotopes relate to this idea?

A

Mass Spectrometry is a method used to analyze precise masses of particles. As isotopes have slightly different masses due to different neutron amounts, you can utilize this method to differentiate different isotopes.

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4
Q

Conceptually explain what occurs to a photon of light as it interacts with an electron of an atom.

A

The photon coming in is absorbed by the electron, causing the electron to move at a velocity. Because an electron has a mass (though small) the electron has kinetic energy. This kinetic energy allows the electron to propel itself out of its original shell and once this occurs, the electron is now called a photoelectron. When enough photoelectrons are produced, they create a flow of electrons called electricity.
Note the photon has no mass, therefore has no kinetic energy.

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5
Q

Conceptually explain the conservation of energy as a photon interacts with an electron of an atom.

A

Energy is conserved throughout the transition of energy from a photon to an electron. Energy of the photon is used transferred to the electron as kinetic energy

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6
Q

Mathematically define the conservation of energy of a photon as it collides with an electron in its principal shell

A

EPhoton = EO + KEPhotoelectron

EO - work function of the element, meaning this is the minimal amount of energy necessary to free the electron. This value varies from metal to metal

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7
Q

What is the work function of an element? What is its importance?

A

EO - work function (WF) of the element, meaning this is the minimal amount of energy necessary to free the electron. This value varies from metal to metal as WF depends on the composition and structure of an element. It plays an important role in thermionic emission

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8
Q

Define kinetic energy

A

KE is the energy of a mass traveling at a certain velocity. Therefore a vector unit as velocity is a vector
KE = 1/2mv2

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9
Q

How do you convert the wavelength of a photon/light into its energy?

A

EPhoton = h(nu) | Planck’s Constant * freq

C = λv | wavelengthfreq

=> v = c/λ then chug v into E Photon equation

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10
Q

Nanometers …

A. 10^-6
B. 10^9
C. 10^6
D. 10^-9

A

D. 10^-9 - nanometers

10^-6 = micro
10^6 = mega
10^9 = giga
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11
Q

If a photon of wavelength 525 nm hits metallic cesium (work function 3.43 10^-19J). What is the velocity of the photoelectron produced?

A

EPhoton = 3.78x10^-19 J = hc(λ) or hν

KE = Ephoton - Eo = 3.78 x10^-19 - 3.43 x10^-19 = 3.5 x 10^-20J

v = ½(9.11 x10-31)v^2 = 3.5 x10^-20J => 2.8 x10^5 m/s

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12
Q

If a photon of wavelength 625 nm hits metallic cesium (work function 3.43 10^-19J). Will this wavelength create photoelectrons?

A

λ= 625 nm

EPhoton = hc(λ) or hν = 3.2x10-19J

No the requirement to produce photoelectrons is an energy of 3.43e-19 (the work function)

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13
Q

In an experiment you focused some photons of 625 nm onto an atom and produced an energy of 3.2e-19, yet there were no photoelectrons generated. If the work function is 3.43e-19, can increasing the intensity of the light generate photoelectrons?

A

No, the intensity or brightness of the light (the amplitude) does not affect the energy created by the photon. No matter how bright this light is, no photoelectrons will be produced.

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14
Q

In an experiment, you focused some photons onto a sheet of gold with a work function of 5.1 eV. How much energy (in joules) is required to produce photoelectrons from this metal?

A

5.1eV (1.6e-19J / 1ev)

= 8.16e-19 (AKA 8.16 x 10^-19)

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15
Q

In this hypothetical experiment you focused some red light onto some copper and produced photon energy of 4.5e-18. This energy did not produce any photoelectrons. If the work function was 4.0e-17, can changing the color of the light produce photoelectrons?

A

Yes, only if changing the color/frequency of the light produces and energy of 4.0e-17 or more.

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16
Q

Define light travel in terms of quantum energy

A

As light is traveling through a medium, it carries a certain amount/quantized of energy

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17
Q

True or false: 4 x 10^-4 = 4e-4

A

True

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18
Q 
Planck’s Constant…. 
A. 6.62e-33m^2kg/s
B. 6.62e-34kgm/s2
C. 6.62e-34kg^2m/s
D. 6.62e-34m^2kg/s
A

D. 6.62e-34m^2kg/s This constant links the amount of energy a photon carries with the frequency of its electromagnetic wave.

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19
Q

6.62e-34m2kg/s is the same as….

A. 6.62e-34 Js
B. 6.62e-34 N/sm
C. 6.62e-34 Jm/s
D. 6.62e-33 Nm/s

A

A. 6.62e-34 J*s. This is the SI units of planck’s constant

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20
Q

Demonstrate the relationship between frequency of a wave and the energy of a photon

A

ΔE = h*f
This equation in particular relates how the frequency or wavelength of a wave can determine the energy of a photon within the wave

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21
Q

In terms of quantum mechanics, what allows an electron to exist in a shell?

A

The electron carries an exact amount of energy in order to orbit within the shell. The energy can not be either too low or too high. Due to this theory, the electron will never be found in between shells.

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22
Q

Differentiate between the excited state and the ground state of an electron.

A

The ground state (Eo) is the energy level/shell in which the electron has the least amount of energy. In the excited state, the electron has absorbed some quantized amount of energy and has jumped further away from the nucleus onto a different shell (exact shell is based on the quantized energy it has absorbed)

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23
Q

Apply Coulomb’s Law to a hydrogen atom. What is required to move the electron further from the proton?

A

According to Coulomb’s law, a PROTON will exert an attractive force to the electron and pull on the electrons. Due to this attractive force, energy/work must be inputted into the system to allow the electron to overcome this force in order to move further from the nucleus.

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24
Q

True or False: Coulomb’s law entails the attractive pull from the electron onto the positive proton in the nucleus

A

False, Coulomb’s law entails the attractive force exerted by the proton onto the electron.

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25
Q

After the electron has been excited. It releases the captured energy and falls back into its ground state. What type of energy is emitted from this electron?

A

The energy is released in a form of light

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26
Q

In Einstein’s many experiments to understand light, he hypothesized that the more intense the light was, the more energy the light carried. Was he correct in his thinking?

A

No, after conducting his experiment, he found that brightness did not affect the electrode. This leads to the conclusion that brightness of an electromagnetic wave does not impact energy, but simply that there is more photons in that wave

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27
Q

In Einstein’s many experiments to understand light, he hypothesized that if energy really is quantized, then increasing the frequency of the wave will lead to more energy in the light. Was he correct in his thinking?

A

Yes, he found that as he increased the frequency of the wave, the light increased in energy and he was able to demonstrate this increase in energy by exciting an electrode to produce electricity. This experiment led to the well known relation of ΔE=hν

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28
Q

When does a light behave like a wave, when does it behave like a particle?

A

Light changes its pattern of behavior when it is convenient. In travel over distances it behaves much like a wave, and when it interacts with specific subatomic particles, it behaves like a particle.

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29
Q

Based on Quantum Mechanics, in order for an electron to move from orbit to orbit, it must absorb a precise amount of energy, nothing more, nothing less. Say a photon is absorbed by an electron, allowing it to move from its ground state, but the left over energy of the photon is not enough for the electron to move another shell. Conceptually elaborate where this energy is transferred to?

A

This energy is transformed into kinetic energy of the electron. Therefore the electron is able to orbit at a much higher velocity in its new orbit.

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30
Q

Describe what ionization of an element is. Relate this idea to mass spectrometry.

A

Ionization is the process of creating a charged atom/particle through the addition of electron(s) or removal of electron(s) creating a negative or positive particle respectively.

This process is important in mass spectrometry because this is the initial step in figuring out the mass of a particle. The particles are vaporized into a gaseous state to create the ions. As ions and gas, the particles are better suited for travel in a magnetic/electric field.

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31
Q

True or False. U-235 -1 is the result of adding an electron to the atom

A

True. Adding an electron makes the originally neutral atom negative. Removing the electron would create a U-235 +1

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32
Q

Identify the travel of a particle in mass spectrometry.

A

The particle is ionized in the Ion Source. Then it is released and allowed to accelerate through a magnet or an electric field where it will separate/deflected based on its mass. The particles hit the detector/Faraday collectors and this sends a current through the amplifier to give the ratio output.

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33
Q

The current produced at the Faraday collector in mass spectrometry entails what?

A

The relative current generated by the ions indicate the relative abundance of the mass in the sample

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34
Q

How is a particle’s mass calculated in mass spectrometry?

A

The mass can be calculated one of two ways: (1) how long it takes the particle to travel a certain distance or (2) the particle’s angle of travel. Both allow calculation of mass to charge ratio (Weight of ion/charge of ion)

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35
Q

As a particle travels through the magnetic field, it gains velocity. What is the final velocity of the Lithium - 7?

A 
Work = charge of ion*potential difference 
= q(Δν) = KE 
= q(Δv) = ½ mv^2
= v^2 = (2q(Δv)/m)
= v = sqrt (2qΔv/m)

Note: Velocity (v) ≠ Potential difference (v)

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36
Q

What is the definition of work. Apply this to magnetism.

A 
Work = force*displacement 
W = F*d

In Magnetism, the work done or the energy transferred (J) is the charge over a potential difference) W = V*q

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37
Q

True or False. The velocity and potential difference are both characterized by v. Due to this, both are the same in units of m/s

A

False, though they both share the same symbol and describe changes of a physical quantity, Potential difference describes the difference of 2 electrical potentials between two different points. Due to this potential difference’s units are measured in Voltage = kgm^2/(s^3*A).

Velocity is the change in meters of an object over time. Therefore units of measurement are m/s

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38
Q

In a mass spectrometer, the positive ion enters a magnetic field pointing out of the page. Due to this, it gains a velocity as a result. Describe the mathematical experience of this ion and the magnetic force produced by the magnetic field

A

Magnetic Force = (Charge of ion)(velocity of Ion)(Magnetic Field)

FB = qvB

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39
Q

The purpose of the ionizing the particles in the ion source is to allow the particles some type of motion to get them going. What is the purpose of having the ions pass through a magnetic field?

A

The magnetic field causes all the ions to have the same velocity. Therefore as the ions are deflected they are separated based on their mass and not because of their velocity.

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40
Q

Even as the Bohr Model is unrealistic, why is it still taught in classrooms today?

A

The Bohr model is great to visualize in order to calculate the radius of an atom and allows understanding of hydrogen atom through quantizing energies of different orbitals

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41
Q

The right hand rule has been modified in many different ways in order to understand the problem at hand and ultimately have created 3 different versions. Describe what each portion of the hand represents in the Lorentz force?

A

Thumb - The current (it always flows from positive to negative
Forefinger/Pointer Finger - the magnetic field
Middle finger - force on the current

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42
Q

In using the Lorentz Right hand rule, what are the two assumptions that have to be made about current and magnetic field?

A
  1. Current flows from positive to negative (even though current is a flow of negative charges!!!)
  2. The force on the current is perpendicular to both the current and magnetic field
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43
Q

Some right hand rules modify the Lorentz Right Hand Rule and use the palm as the to demonstrate the force of ON the current. What does it actually mean?

A

The palm is meant to represent the current field force (open hand). NOT the force on the current
(arbirsci.com)

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44
Q

The purpose of Oersted’s Law is to demonstrate…

A

This is another right hand rule that takes into account only 2 variables: the flow of current and the magnetic field. This is also known as Right hand curl or Ampere’s law

Thumb - the current

Fingers wrapping - magnetic field

45
Q

When is it most appropriate to use Ampere’s right hand rule?

A

When the problem deals with long straight wires

arborsci.com

46
Q

When is it most appropriate to use the Lorentz’s right hand rule?

A

When the problem deals with a free moving charge in a magnetic field.

47
Q

As a positive molecule, created by the ion source, enters into a counterclockwise magnetic field with the current pointing straight out of the page, what is the direction of the ion induced by this force?

A

The direction of the magnetic force is to the right so the ion entering the field will be pulled and directed into the right as there is a 90 degree angle between the velocity of the current and the force of the magnetic field. This force deflected the ion and caused it to move in a circle.

48
Q

In a mass spec test, you let your ion run through the magnetic field. However, you forget to turn the magnet on. What is the direction of this accelerating particle?

A

The ion will travel in a linear direction straight from the ion source because there is no net force acting to change its direction

49
Q

Why would an ion ejecting from an ion source during a mass spec test, move in a circle?

A

The uniform magnetic field is perpendicular to the velocity, so the ions follow circular paths.
(Physics.bu.edu)

50
Q

Assess this equation: r = √[(2mV)/(qB^2)] How is this equation relevant to the studies of mass spectrometry?

A 
r = the radius of the ion travel in the magnetic field
m = the mass of the isotope
q = charge of the ion 
B = Magnetic Field
v = velocity

Can also be written as r = mv/qB or mEs/qB1B2. This implies the particles spin is cylindrical (pstcc.edu)
[Don’t emphasis on this too much]

51
Q

When does F = qvB = F = qvB sin θ

A

This is only the case when the angle (θ) between the velocity and the magnetic field are perpendicular to one another. [note: sin 90 = 1] when the two are not 90 degrees to one another, then you have to include the sin of their angle

52
Q

A sample of carbon is placed into the mass spectrometer and after the tests have been run, you find the sample contains both C-13 and C-12. Which isotope will have the smaller radius as it travels in the magnetic field?

A

C-12 willhave a smaller radius because it has a smaller mass according to r = √[(2mV)/(qB^2)]

53
Q

What are the most likely uses of mass spectrometer in today’s real world problems?

A

Mass spec is no longer used to identify differences in isotopes but more utilized in evaluating precise masses of an object?

54
Q

In a chamber such as a mass spec where the force exerted onto a particle (the magnetic force) is constant, what really determines the acceleration of the object moving?

A

When force is constant, the only thing determining how has something is moving is the mass of the object according to F = m*a. Therefore the bigger the mass, the slower the object moves

55
Q

You leave the mass spec running as you go and grab some lunch. You come back and check the detector and find there are 3 specific markings. What can you conclude about distances and mass?

A

The further the travel the bigger the mass of the particle because the detector is a function of mass
r = m*v/qB

56
Q

What is a parent peak in mass spec?

A

The parent peak is produced by the parent ion. This is the molecular weight of the molecule of focus and when the charge of this molecule is equal to positive one, there should be a direct peak at this m/z

57
Q

Compare and contrast base peak and parent peak in a mass spec test.

A

Base peak and parent peak do not necessarily have to equal to one another. Base peak given to a peak that demonstrates the most ion of the whole sample. When we do this, we assign it with abundance 100. When we do this, we are essentially comparing all other fragments against this one peak.

58
Q

What is p + 1 peaks?

A

This is the slightly heavier particle/isotope of the parent ion

59
Q

If we place only C - 12 and C - 13 into a mass spec, we should only expect 2 fragments created. Why are there sometimes other smaller peaks surrounding our two isotopes of interest?

A

The fragmentation pattern is the result of ionizing the particles. This can create fragments of our particles and there are lower in mass

60
Q

You run a mass spec experiment on a nitrogen sample and find there are no fragments in the detector. Is the sample you tested massless?

A

No, the error could lie in:

  1. Perhaps as a result of no ionization in the ion source. The detector is only able to identify ions, and without this step, there won’t be any detection if the ion was able to travel, and if no ionization, there ton’t be travel.
  2. The magnetic field was not turned on. Without the magnetic field, the ion would run straight ahead and not be deflected onto the detector.
61
Q

Define light travel in terms of quantum energy

A

As light is traveling through a medium, it carries a certain amount/quantized of energy

62
Q

True or false: 4 x 10^-4 = 4e-4

A

True

63
Q

Describe the travel of an electron as it orbits the nucleus. What is preventing the electron from traveling in a continuous line into space away from the nucleus?

A

The electron’s velocity is tangent to its orbit. However, the electron is pulled to the nucleus due to the attractive force of the proton. This force produced is the centripetal force, which acts on the to keep the electron moving in a circular path.

64
Q

True or false - The centripetal force keeping the electron of a hydrogen atom in circular motion is also the electric force

A

True. The electric force is the force between two charged objects (repulsion or attraction) This attraction causes the centripetal force (the force or pull felt by the electron to circulate the electron) to exist.

65
Q

Mathematically Find the Electric force (F sub e) through Coulomb’s law:

A

Fe = (kq1q2)/r^2

K = Coulomb's Constant of 9e9 N*m^2/C^2 or kgm^3/(s^2*C^2)
q1= Charge of particle one, can be any particle unless other wise specifies
q2 = Charge of particle 2
r = radius
66
Q

An electron is orbiting in a uniform, circular pathway in its orbit due to the centripetal force. Identify the direction of the centripetal acceleration.

A

The centripetal acceleration is in the same direction as the centripetal force. Both are pointing from the electron to the center. Both have to be in the same direction because Fc = m*ac [Remember the two vectors have to be in the same direction as one another for this relationship to exist and note: Tangent acceleration does not have the same direction as the centripetal acceleration]

67
Q

The centripetal acceleration is the change in centripetal velocity over time. However, how else can you describe this type of acceleration in terms of radius since it is creating a circular pathway?

A 
a_c = v^2/r 
v = velocity of the object
r = radius
68
Q

Are you able to define the mass of an electron in angular motion from the electric force it is feeling?

A

Fe = Fc
kq1q2/r^2 = mac
kE^2/r^2 = m(v^2/r)
=> kE^2/r = m*v^2

69
Q

Define what momentum. What is the difference of angular momentum from transitional momentum?

A

Momentum (p) is a quantity of motion of a moving body measure by mass*velocity. Angular momentum (L) is the measure of momentum of a body in circular motion. Therefore L = r X p (the cross product)

70
Q

Is momentum and kinetic energy the same concept?

A

Momentum is a vector measurement of the amount of mass in motion. KE is the scalar measurement of the object’s energy in motion.

71
Q

The cross product of angular momentum focuses on what two variables?

A

The radius and the velocity of the object

L=mvr

72
Q

When you quantize angular momentum, therefore set a discrete value to it, what does this allow?

A

Bohr did this by setting angular momentum to planck’s constant and an integer, n, the principal quantum number. Therefore L = n*h. In order to maintain the same units of interest, after some math, Bohr discovered dividing 2π

L = n*h/2π

73
Q

Find the velocity of a moving electron of a hydrogen atom, if it’s orbiting 2 shells away from the nucleus, which creates a radius of 5.3 e-11 away from the nucleus.

A 
v = nh/2pi*m*r
v = 2*6.62e-34/(2*pi*9e-31*5e-11)
v = 4e6 m/s
74
Q

The radius for the principal quantum number is r = 5.3e-11m. Why is this an important value?

A

This is a radius of a ground state electron, specifically the first orbital shell from the nucleus. This the smallest radius in the bohr model. This also means that through this formula, rn = n^2r1 the radius of each principal quantum shell, where R1 = 5.3e-11. Therefore this also means only specific radii sizes can exist as well.

75
Q

Find the radius of an electron traveling in the second shell away from the nucleus.

A

r_n = n^2r_1 => 2^2r1 => 4*r1 => 4(5.3e-11) = 2.12e-10

76
Q

After some calculations in your quantum theory class, you find that the radius of different shells are discrete such as when n=2, r=2.2e-10 m and when n=3, 4.77e-10 m. Is there other radii in between these meters?

A

No. Because radii are assumed to be discrete/quantized much like the energy required to travel at this length away from the nucleus, there are no other radii possible in between these two shells

77
Q

Describe what principle quantum numbers (n) are.

A

This describes the energy of an electron and the most probable distance of the electron from the nucleus. Therefore this number refers to the size of the orbital as well. The higher n is, the more energy the electron needs to have to remain in this orbit.

78
Q

Explain what happens to the electron of a room temperature hydrogen atom in principle quantum number of n = 1 as it is heated.

A

As the molecule is heated up, the electron gains energy and is able to move to its excited states depending on how much energy it was able to gain.

79
Q

As a glazier hammers away at the glass, sparks of red fly from the object. What is allowing these atoms to glow bright red?

A

The hot red emitting from the atom is a result of the excited electrons releasing the energy to return to its ground state. The energy from the electron is released as a single photons and these photons are the ones create the spectra lines

80
Q

What are the spectra lines?

A

These are the lines produced as a result of light emission or absorption

81
Q

What is the trend in the energy of an electron as we go higher in the line spectra?

A 
The energy of the electron increases therefore becomes less negative. This means that in order for an electron to be further away from the distance, it needs to have more and more energy 
Ex: Hydrogen model
n = 3; E = -1.5eV
n = 2 ; E = -3.4eV
n = 1; E = -13.6eV
82
Q

True or false: As an electron moves from a higher level, it releases a single photon with an energy equal to the number of levels it moves down. Therefore, as it moves from n=3 to n=1, a photon of 12.2eV is released from the atom.

A

False. Each level corresponds to a single photon. Therefore from n = 3 to n = 1, two photons should be released from the atom, each one with a different wavelength as they are different energies `

83
Q

What is the color of light released as an electron moves from orbital 3 to orbital 2?

A

S1: E3 - E2 = -1.5 - (-3.4) = +1.9eV (this is the energy released in the photon)
S2: If 1 ev = 1.62 x 10-19 J then 1.9eV (1.62x10-19 J/eV) = 3.04 x 10-19 J
S3: E = hν => hc/λ =
λ = hc/E = 654nm (red color)

84
Q

Even as most electromagnetic wavelengths along with visible spectrum are not distinct, what is the general rule of thumb for identifying the colors with their wavelengths?

A 
Violet - 380 - 450 nm
Blue - 450 - 500 nm 
Green - 500 - 570 nm
Yellow - 570 - 590 nm
Orange - 590 - 620 nm 
Red - 620 - 750 nm

Mnemonic: Violet took the 380 Hw and exited the 450 Junction to go to Walmart. When she reached the blue walmart sign, she noticed it was 5:00 (500nm). She bought some green apples for 5.70 and some yellow onions for 5.90. As she got into her orange car, she realized the time was 6:20 (620 nm) and once she was one red light away from her house, she noticed it was 7:50 pm

85
Q

Analyze this equation: F = kq1q2 / (r2) What are its uses?

A

This is the Energy Wave Theory in which electric force (Fe) is pulling the electron towards the center by the proton. Destructive wave interferences leads to an attraction of two particles which produces motion and is measured as Fe (energywavetheory.com)

k or ke - Coulomb’s constant aka the electric force constant or electrostatic constant 8.9 x10^9 (kgm^3)/s^2C^2

q’s - are the charges of the two particles of focus and r is the radius as which the two particles are away from each other

Equation is used to understand the attraction between two charged particles

86
Q

If two particles with a destructive wave stores their energy instead, such as the electron’s position in an atom, what results instead of electric force?

A

It may result in a photon explained by planck relation => E=hf

87
Q

In trying to find the velocity of an electron orbiting, we reach a point when we set up the electrostatic force to the mass*centripetal acceleration of the electron and get => F = kq1q2/r^2 = mv^2/r If the electrostatic force is destined to be negative due to the charge of the electron, does this imply that either the velocity, radius, or mass of the kinetic energy will be negative as well?

A

No. velocity, mass and radius can’t be negative AND since we only care about the magnitude, we NEED to take the absolute value of the electrostatic force

88
Q

Compare and contrast acceleration to centripetal acceleration.

A

Acceleration (a) = Δv/t

Centripetal acceleration (ac) = v^2/r | The acceleration of an object moving in an angular motion is modified to include the radius rather than the time.

89
Q

What is the purpose of setting electrostatic force of an electron to Newton’s second law?

A

The purpose is to understand either the mass or the centripetal acceleration/its variables. You’re also able to understand the kinetic energy of this moving mass as well. After some simplification, you are able to set the electrostatic force to the kinetic energy of the electron and find the velocity of the electron

Fe = kq1q2 / (r2) = m*a = F [Newton’s second law]

Fe = kq1q2 / (r2) = m*ac [because this is angular motion]

kq1q2 / (r2) = m*v^2/r

Cancel radius on both sides -> kq1q2 / r = m*v2

Multiply ½ to both sides -> ½ kq1q2 /r = ½ m*v2

KE = ½ kq1q2/r
Note: q1q2 can also be set to e^2 (they mean the same thing and only take into account of the magnitudes rather than the signs)

90
Q

How does gravitational potential energy (Ug/PEg) differ from electric potential energy (Ue)

A

Ug/PEg = mgΔh
m = mass
g = acceleration due to gravity
Δh - distance above surface

Ue = kq1q2/r 
k = constant
q1 = charge of subatomic particle 1
q2 = charge of subatomic particle 2
r = distance bt subatomic particle 1 and 2
91
Q

Based on the Electric potential energy’s equation, the value is mostly like going to be negative. What causes this? Should we take the absolute value of it, which is done in determining the electric kinetic energy?

A

The q of the electron will cause the Ue to be negative.

And no, the negative sign is important to determine how much energy is required to remove the electron out of its position, therefore the absolute value should not be taken.

92
Q

Much like the translational total energy of an object, how is the total energy of an electron similar?

A

Total energy of an electron = electric kinetic energy + electric potential energy
∑ E = Ek + Ue
∑ E = ½ kq1q2/r + kq1q2/r [note Ek and Ue are very similar!!!!]

93
Q

The electrostatic constant is equal to:

A. 9 x 10^9 (kgm^3)/s^2C^2
B. 9 x 10^10 (kgm^3)/s^2C^2
C. 1.6 x 10^-10 C
D. 1.6 x 10^-9 C

A

A. 9 x 10^9 (kgm^3)/s^2C^2 ] SI units.

94
Q

A proton and an electron have the same magnitude of charge:

A. 9 x 10^12 (kgm^3)/s^2C^2
B. 9 x 10^13 (kgm^3)/s^2C^2
C. 1.6 x 10^-13 C
D. 1.6 x 10^-12 C

A

C. 1.6 x 10^-13C

95
Q

Knowing that the lowest energy level of an electron is E = ½ kq1q2/r, how can we modify this to find the different energies based on the energy levels.

A

En = E/n^2
Therefore is the -13.6 eV is the lowest E possible then
=> En = -13.6/n^2 where n = the principal number
Note: E = ½ Kq1q2/r; q1q2 can also be set to e^2 (they mean the same thing and only take into account of the magnitudes rather than the signs)

96
Q

Find the energy of the an electron in a hydrogen atom in the first orbital in electron Volts

A

E_n= E_1/n^2
E_1 = -2.17 x 10-18J
-2.17 x 10-18J (1 eV/1.6 x 10-19 J) = -13.6 eV (this is the lowest energy in hydrogen)

97
Q

In determining what amount of energy needs to be inputted into an atom to free an electron from its ground state, you come across the E = 0. What does this mean?

A

When En = 0, this means the electron is no longer in orbit with the nucleus as there is no longer any attraction! Therefore there is no need to input any energy into the system further.

98
Q

In terms of electrostatic quantities, define ionization.

A

This is when the electron has received enough energy to leave the atom’s orbit. At this point, the electron no longer feels any electric kinetic energy or electric potential energies.

99
Q

How much energy is required to completely release an electron from its ground state in a hydrogen atom?

A

It takes -13.6 eV to take an electron from a neutral hydrogen (ONLY) to ionize it and remove it from orbital with the nucleus
En = -13.6eV/n^2
En = -13.6eV/1 => +13.6eV needs to be imputed into the system

100
Q

How much energy is required to completely release an electron from n=4 in a hydrogen atom?

A 
En = -13.6eV/n^2 
En = -13.6eV/4^2
En = -13.6eV/16 => -0.85eV therefore you need to input 0.85eV to release this electron from principal shell 4
101
Q

Rutherford’s planetary model was quite inaccurate in depicting an actual atom, leading to the adoption of the Bohr’s model. What did Rutherford lack in his model?

A

A. Didn’t incorporate that energy is quantized

B. Didn’t explain the line spectrum produced by individual atoms (failed to explain why indv atoms released electromagnetic radiation with specific frequencies)

102
Q

The adoption of the Bohr model became quite famous in the 1900’s. What did it offer that the Rutherford model could not?

A

A. Electrons move about a nucleus in a circular, discrete quantity of energy. As the electron moves around, it DOES NOT radiate any energy (therefore it does not gain or lose any energy)

B. It explains how an electron loses or gains energy. Each possible orbit is called a stationary state. The electron only emits or loses energy when the electron moves from a higher orbit to a lower orbit. And conversely, when it moves from a lower energy to a higher, it gains energy

103
Q

In mathematical terms, define the energy of a photon lost as an electron emits energy while it transitions from a high energy state to a lower/ground state.

A

EHigher - ELower = EPhoton = h(f)

104
Q

True or False. All elements’ electron’s ground state is when n = 1

A

False. Ground state is unique to an electron. Therefore the ground state of an electron in hydrogen is different from the ground state of a carbon orbiting in shell 2. This shell is the orbit where they are found to have the lowest energy AND closest to the nucleus

105
Q

Compare and contrast absorption and emission by an electron.

A

When the electron becomes excited, this process is called absorption - The electron absorbs energy. Emission is when it releases energy, it emission, because emits a photon (light), which has a certain wavelength

106
Q

What is the purpose of Rydberg’s constant? When is it used?

A

It simplifies the math by taking planck’s constant, speed of light, and lowest ground state and converting it to a value. R = 1.1 × 107 per metre

It is most useful to solve electrostatic equations such as defining wavelengths of a photon released

107
Q

What does the Balmer Rydberg Equation tell us?

A

1/Lambda = R(1/J2 - 1/I2)
Explains the different wavelengths of light emitted by an electron as it falls from a high energy level to a lower energy level.

108
Q

What is the equation for magnetic force in terms of magnetic field strength and velocity of an ion?

A 
F = qvB
F = Magnetic force
q = Charge of ion
v = velocity of ion
B = Magnetic field Strength
109
Q

Which equation can be used in tandem with F = qvB in order to calculate the mass of an ion in a mass spectrometer based on the radius of the circle?

A

Fc = m(v2/r)

GC/OC (5 decks)

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