Unit 4 - light and electron trends Flashcards

1
Q

4 characteristics of waves

A

Amplitude, wavelength, frequency, speed

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2
Q

amplitude

A

the height of the waves from the orgin to the peak or crest. this adjusts brightness or intensity of the light - not the type of light itself

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3
Q

wavelength (λ)

A

the distance from peak to peak (determines the type of light)

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4
Q

frequency (v)

A

how fast the wave oscillates (determines the type of light), measured in hz, 1/s

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5
Q

speed

A

the speed of light is constant
formula: 3.00x10^8 m/s

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6
Q

~~~

A

long wavelength, low frequency, low energy

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7
Q

what is the relationship between wavelength (λ) and frequency (v)

A

inverse

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7
Q

^^^

A

short wavelength, high frequency, high energy

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8
Q

formula for wavelength and frequency

A

speed of light = (wavelength) (frequency)

c=λv

λ - meters
v - 1/s

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9
Q

how would you find the frequency of red light that has a wavelength of 650nm

A

1 - convert nm to m
2 - plug into the formula v=c/λ

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10
Q

what is the relationship between energy (E) and frequency (v)

A

direct

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11
Q

which has a shorter wavelength - red or violet light?

A

violet

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12
Q

formula for energy and frequency

A

Energy = (Plank’s constant)(frequency)

E = hv

h - plank’s constant
v - 1/s

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13
Q

as the wavelength gets longer, does the frequency get higher or lower?

A

lower

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14
Q

as the frequency increases, does the energy increase or decrease?

A

increase

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14
Q

which has a higher frequency - red light or violet light

A

violet

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15
Q

which is more energetic - red or violet light?

A

violet

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16
Q

what do you see when you look at sunlight through a spectroscope?

A

a rainbow/all of the colors (ROYGBIV)

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17
Q

what gas is inside a fluorescent lightbulb

A

mercury

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17
Q

T or F - every element has its own emission spectra

A

T

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18
Q

gravitational potential energy

A

since gravity attracts an object towards earth, an object will store potential energy depending on its height above earth

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19
Q

Electric potential energy

A

since opposite charges attract (by the electrostatic force), an electron can have stored potential energy depending on how close the electron is to the nucleus

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20
Q

what is potential energy converted into

A

light

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21
Q

Bohr model of the atom

A

in an atom, electrons can only exist in distinct energy levels. this means that the energies of the electrons in atoms are quantized

using the emission spectrum of hydrogen, Neils Bohr was able to determine the specific discrete energies that are possible for a single electron to have when in a hydrogen atom

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21
Q

quantized

A

the possible number of energy values of an electron are negative, electrons reside on specific energy levels

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22
Q

what happens to the electron in hydrogen when electricity is sent through hydrogen gas

A

1 - the electrons absorb energy from the electricity and they jump up to a higher energy level, gaining potential energy

2 - since the electron is attracted to the nucleus by electrostatic force, the e- falls back down to a lower energy level and releases energy in the form of light

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23
Q

what attracts electrons to the nulceus

A

electrostatic force

23
Q

since electrons are attracted to the nucleus, it is relatively difficult to move an e- further away from the nucleus. Thus, when an electron does not move further away from a nucleus, energy must be…

A

absorbed by the electron

23
Q

when an electron moves further away from the nucleus, the electron must…

A

gain potential energy

24
Q

what happens to electrons when they absorb energy

A

they jump to a higher energy level, gaining potential energy. then, the electrons will be attracted to the nucleus through electrostatic force, thus releasing energy in the form of visible light (specifically a photon of light)

25
Q

orbitals

A

electrons do not “orbit” in a defined path around the nucleus. Instead, for a particular energy electron, one can only know the most probable locations to find the electron. Thus, we say that electrons are in orbitals.

26
Q

describe the S orbital

A

1 orientation, spherical shape

26
Q

describe the p orbital

A

3 orientations (aligned on x, y, and z axis), peanut shape

27
Q

describe the d orbital

A

5 orientations (along different planes), four-leaf clover shaped

28
Q

describe the f orbital

A

7 orientations, shape has 8 lobes (flower shaped)

29
Q

overlap of sublevels

A

as one goes up, the energies of the energy levels get closer and closer to each other. thus, the energy levels overlap more and more as one goes up

30
Q

order of sublevels

A

1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s

30
Q

Aufbau principle

A

fill the lowest energy level first

31
Q

pauli exclusion principle

A

there can be a maximum of only 2 electrons per orbital with opposite spins

31
Q

why are electrons represented by arrows when writing electron configuration

A

because they spin clockwise and counterclockwise

31
Q

Hund’s rule

A

when filling a sublevel, there should be a maximum number of unpaired electrons before pairing them up

31
Q

shielding effect

A

more shielding e-‘s block the valence e-‘s from feeling the positive pull of the nucleus while Zeff remains the same

32
Q
A
32
Q

what is Zeff

A

effective nuclear charge
the Zeff is the amount of positive charge that is effectively attracting the valence electrons

32
Q

octet rule

A

atoms will lose, gain, or share e-‘s in order to have 8 in the outer shell

33
Q

Atom size vs. Ion Size

A

atom is less than negatively charged ion

atomic size:
as you move across the periodic table, atomic size generally decreases

positive ionic size:
these atoms have lost e-‘s, resulting in a positive charge. typically SMALLER than their parent atoms because losing e-‘s reduces the amount of shielding e-‘s and allows remaining e-‘s to be pulled closer to the nucleus

negative ionic size:
these atoms have gained e-‘s, resulting in a negative charge. typically LARGER than parent atom because gaining e-‘s increases the # of shielding e-‘s, thus reducing Zeff

34
Q

what is ionization energy

A

the amount of energy needed to remove an e- from an atom

35
Q

why does ionization energy decrease moving down a family/column

A

it will be easier to remove an electron because it gets further from the nucleus, thus the Zeff decreases. therefore, the IE decreases as well because it will be easier to remove an e-

36
Q

why does the IE increase moving across a period

A

the IE will increase because the radius of the atom decreases and the valence e- gets closer to the nucleus. Thus, the e- will be harder to remove and the IE will increase.

37
Q

which element has higher ionization energy - C or O

A

O

37
Q

which element has higher ionization energy - Na or K

A

K

38
Q

do metals or non metals have higher ionization energy

A

nonmetals

38
Q

what is meant by a second or third ionization energy / successive ionization energy

A

the shielding e-‘s become the new valence e-‘s and the size of the atom decreases. Thus, the IE is stronger and the e- is harder to remove from the atom.

39
Q

why do noble gasses have particularly high ionization energies

A

the valence e-‘s are closer to the nucleus and they have a “full outer shell”

40
Q

what is electronegativity

A

electronegativity is the relative tendency of an atom to attract electrons towards itself from another atom in a bond

41
Q

if an atom has high electronegativity, the atom _______ attracts electrons

A

strongly

41
Q

why does electronegativity decrease moving down a family

A

there are less shielding e-‘s in the smaller atom, therefore it will strongly attract e-‘s.

42
Q

why does electronegativity increase when moving across a period

A

as they move across the periodic talbe, atoms get smaller and there are less shielding e-‘s in the atom. therefore, it will strongly attract e-‘s.

42
Q

in general, which have higher electronegativities (metals or non-metals)

A

nonmetals

43
Q

if Na and Cl bonded together to make NaCl, which atom would attract the e-‘s more strongly

A

Cl

43
Q

which elements have the three highest electronegativities

A

F O N (especially F)

44
Q

if Mg and O bonded together to make NaCl, which atom would attract the e-‘s more strongly

A

O

45
Q

which has the smaller radius
F or F-
Na of Na+
Ca or Ca+2
N or N-3

A

F-
Na
Ca
N-3

46
Q

which elements tend to lose e-‘s and form positive ions and why

A

metals (metals are LOSERS)

46
Q

describe the process of fluorescence

A

Excitation: A material absorbs a photon and transitions from its ground state to an excited state.

Fluorescence lifetime: After a brief period, the material returns to its ground state, emitting a photon with lower energy.

Emission: The emitted photon has a different frequency, resulting in the characteristic fluorescent glow

46
Q

what is phosphorescence

A

“glow in the dark”
the electrons are able to absorb energy quickly and lose it slowly as they fall back down to ground state

47
Q

what is triboluminescence

A

Charge Separation: When a material is mechanically stressed, its surface can become electrically charged due to the triboelectric effect. This effect occurs when two materials come into contact and then separate, causing electrons to transfer from one material to the other.

Electrical Discharge: The separated charges can create an electrical discharge when they reunite. This discharge can ionize nearby gas molecules, causing them to emit light.

Energy Release: The mechanical action can also give electrons energy, and when these electrons return to a more stable state, they release light.

the crystals tend to break on a plane with one side of negative particles and one side of positive particles. When a crystal is broken, negative charges bridge the gap between the two planes. The electrons primarily emit energy in the form of UV light.