Electromagnetic Spectrum Flashcards

1
Q

What is electromagnetic radiation described as

A

Can be described as a wave and as a particle therefore said to have a dual nature

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2
Q

What is the forumla for wavelength

A

C=f x lambda where c is the speed of light (3.0x10 to the 8)

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3
Q

What happens when electromagnetic radiation is absorbed or emitted by matter

A

It behaves like a stream of particles, these particle are known as photons

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4
Q

What equation is used to calculate the energy associated with a single photon

A

E=hf where h is planks constant (6.63 x 10-34 Js)

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5
Q

What is the equation used to calculate the energy associated with one mole of photons

A

E=Lhc/ lambda where L is avogadros constant (6.02 x 10 to the 23 mol-1)

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6
Q

What happens when a photon is emitted or absorbed

A

The electrons within the substance gain or lose energy

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7
Q

Compare photons in high and low frequency radiation

A

Photons in high frequency radiation transfer more energy than photons in lower frequency radiation

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8
Q

What happens in emission spectroscopy

A

High temperatures are used to excite the electrons within atoms in the sample and as the electrons drop to lower energy levels photons are emitted and measured.

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9
Q

How is an emission spectrum of a sample produced

A

By measuring the intensity of light emitted at different wavelengths

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10
Q

What happens when photons of light energy are absorbed by atoms

A

Electrons move from a lower energy level to a higher one. As this happens an absorption spectrum is produced

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11
Q

What is used to identify and qualify elements

A

Each element produces a unique pattern of frequencies of radiation in both emission and absorption spectra which are used to indentify and qualify

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12
Q

What is used to determine unknown concentrations of an element

A

The concentration of an element within a sample is related to the intensity of light emitted or absorbed and that is used

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13
Q

What is electromagnetic radiation

A

A form of energy. The electromagnetic spectrum consists of many bands of electromagnetic radiation which differ in energy, wavelength and frequancy

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14
Q

What visible light

A

Form of electromagnetic radiation and is split into seven colours and colours are in the order ROY G BIV

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15
Q

Whats the order of the electromagnetic spectrum

A

Radio waves, microwaves, infrared light, visible light, ultraviolet, x-rays, gamma rays

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16
Q

What colours in the visible light spectrum have a higher and lower frequancy

A

Red end has a lower frequancy, purple end has a higher frequancy

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17
Q

Whats a wavelength

A

Is the distance between adjacent crests given by symbol lambda

18
Q

Whats the frequency

A

Is determined by the number of wavelengths that pass a fixed point in one second, measured in hertz

19
Q

What speed does the electromagnetic spectrum travel at

A

A constant speed, which is the speed of light 3,0x10 to the 8

20
Q

Whats the formula that relates wavelength and frequancy

A

C= fx lambda

21
Q

What do photons which have high frequencies do

A

Transfer larger amounts of energy than photon of lower frequencies

22
Q

What happens when a beam of white light is passed through a prism

A

A continuous spectrum is visible

23
Q

What happens when white light passes through a sample being heated

A

The spectrum turns out not to be continuous but a series of lines of different wavelengths and thus different colours, each line corresponds to the energy given out when excited electrons move down to a lower energy level generating photons

24
Q

What does each element do

A

Creates its own unique spectrum with its own specific frequencies and wavelengths

25
Q

What happens when a beam of white light is directed through a gaseous sample

A

Cause an atom to make a transition from its ground state to an excited state

26
Q

When is the photon of light absorbed

A

If the frequency of light, and therefore the energy of a photon corresponds to an excitation energy of an atom

27
Q

Whats an atomic absorption spectrum

A

When radiation has certain wavelengths missing. These show up as dark lines on the continuous spectrum and are called this

28
Q

Whats emission and absorption spectroscopy used to determine

A

Whether a certain species is present in a sample and how much of it is present

29
Q

How are the different types of radiation arranged

A

In order of wavelength and is known as the electromagnetic spectrum

30
Q

What are the units for wavelength expressed normally

A

Nm

31
Q

What does a photon carry

A

Quantised energy proportional to the frequency of radiation

32
Q

What are the formulas for energy associated with a single photon

A

E=hf for frequancy and E=hc/lambda for wavelength

33
Q

What are the formulas associated with one mole of photons

A

E=Lhf for frequancy and E=Lhc/lambda for wavenlgth

34
Q

What happens when energy is transferred to atoms

A

Electrons within the atoms may be promoted to higher energy levels

35
Q

When does an atom emit a photon of light energy

A

When an excited electron moves from a higher energy level to a lower energy level

36
Q

What provides direct evidence of energy levels

A

The light energy emitted by an atom produces a spectrum that is made up of a series of lines at discrete energy levels.

37
Q

What happens in absorption spectroscopy

A

Electromagnetic radiation is directed at an atomised sample. Radiation is absorbed as electrons are promoted to higher energy levels

38
Q

How is an absorption spectrum produced

A

By measuring the intensity of absorbed light varies with wavelength

39
Q

What happens in emission spectroscopy

A

High temperatures are used to excite the electrons within atoms. As the electrons drop to lower energy levels, photons are emitted

40
Q

How is an emission spectrum of a sample produced

A

By measuring the intensity of light emitted at different wavelengths

41
Q

What happens in atomic spectroscopy

A

The concentration of an elects within a sample is related to the intensity of light emitted or absorbed