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Chem 103 > Experiment B: Atoms and Line Spectra > Flashcards

Experiment B: Atoms and Line Spectra Flashcards

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1
Q

What are the the three objectives

A

Use visible light spectroscopy:

  • record the atomic line spectra for 3 elements using a series of gas discharge tubes
  • do flame tests on a series of metal salts
  • record the absorption line spectra of two diff colour smarties
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2
Q

Gaseous discharge tubes emit light of a ______ spectrum

Atoms of the gas are excited by passage of an ____ _____

A

Discontinuous electric current

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3
Q

When excited atoms return to a lower state, a ___ is emitted

A

Photon

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4
Q

Atoms of the gas are excited by passage of an electric current from an _____ at one end of the tube to an ______ at the other end

A

Electrode

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5
Q

How are wavelength and energy determined

A

By the energy levels for that element

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6
Q

What are the two common applications of light emission by elements

A

Flame test and fireworks

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7
Q

What is a flame test used for and why

A

To identify the presence of elements

A bit of the solid is atomized and excited in a flame, this is identified by resultant colour of flame

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8
Q

What variable represents nuclear charge

A

Z

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9
Q

Formula for speed, wavelength, and frequency

A

c= lambda(freq)

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10
Q

What is energy of a photon equal to (2 equations)

A

E = hv = hc

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11
Q

List the colours in INCREASING wavelength

A

violet, blue, green, yellow, orange, red

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12
Q

What are the two formula for energy with “n”

A

E = (-Z^2(Rh))/n^2

triangle E =( -Z^2(Rh))(1/nf^2 - 1/ni^2)

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13
Q

What is the Lyman series

A

ni —-> nf = 1

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14
Q

What is the balmer series

A

ni —-> nf=2

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15
Q

What is the Paschen series

A

ni —-> nf= 3

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16
Q

What does the spectrometer measure

And how (3)

A

The absorption spectra of aqueous solutions of the dyes coating the smarties

1) Light from source is split into a narrow range of wavelengths and passed through the sample

2) some of that might be absorbed

3) spectrometer will obtain values of “A” as wavelength changes

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17
Q

What is the graph of that we printed out

A

“A” vs. Wavelength of incident light
= spectrum

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18
Q

What is the function “A” on the spectrometer

Abs what is it related to

A

Absorbance

Directly related to the amount of absorption

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19
Q

What does a larger “A” value mean on the spectrometer

A

More of the incident light is absorbed

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20
Q

Experiments procedure for the discharge tubes

A

To observe the line spectra: set square hole of spectroscope at the middle of, almost touching the discharge tube

If you place it too far away you’ll see lines for lights in the room

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21
Q

Experimental procedure for flame tests (2)

A

1) dip tip of Pt wire into concentrated H and heat tip of flame, repeat

2) put a solid crystal of LiCl on wire and heat tip on flame

22
Q

What are the compartments inside the spectrometer called

(2)

A

Big compartment = sample compartment

Small containers inside = cuvette

23
Q

For the discharge tubes, the lines in the spectroscope that don’t come close to matching calculated lines are due to what?

A

Human error

24
Q

What does the shortest wavelength correspond to for all the series

A

n = inf to n=2

25
Q

What does the longest wavelength correspond to for all series

A

n=3 to n= 2

26
Q

Formula for flame tests

A

Thermal energy in flame is approx =
R(temp)

Temp in kelvins

27
Q

What colour was LiCl in the flame

A

Flame changed red

28
Q

What colour was BaCl in the flame

A

Flame changed green

29
Q

In the discharge tube what was the wavelength of HYDROGEN and the colours of the lines

A

Around 520 nm

Pink and green

30
Q

In the discharge tube what was the wavelength of HELIUM and the colours of the lines

A

600,500, and 400 nm

Red, green, blue

31
Q

In the discharge tube what was the wavelength of NEON and the colours of the lines

A

600 and 500 nm

Orange, green, yellow

32
Q

When stating the wavelengths for flash cards what are they measured in

A

Metres

33
Q

Wavelengths for gamma rays

A

10^-16 to 10^-12

34
Q

Wavelength for x rays

A

10^-10

35
Q

Wavelength for UV light

A

10^-8

36
Q

Wavelength for Infrared

A

10^-6 to 10^-4

37
Q

Wavelength for microwaves

A

10^-2

38
Q

Frequency for gamma rays

A

10^24 to 10^20

39
Q

Frequency for x rays

A

10^18

40
Q

Frequency for UV

A

10^16

41
Q

Frequency for infrared

A

10^14 to 10^12

42
Q

Frequency for microwaves

A

10^10

43
Q

Red wavelength

A

740-625

44
Q

Yellow wavelength

A

590 to 565

45
Q

Green wavelength

A

565-520

46
Q

Blue wavelength

A

500 to 435

47
Q

Purple wavelength

A

435-380

48
Q

Red freq

A

480-405 Thz

49
Q

Yellow freq

A

530-510

50
Q

Green freq

A

580-530

51
Q

Blue freq

A

580-675

52
Q

Purple freq

A

700-790

Chem 103 (13 decks)

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