Electro Spectro

Question 1

what is electromagnetic radiation?

Answer 1

waves that have both wavelength and frequency

Question 2

what is the symbol and unit of wavelength?

Answer 2

lambda, metres
usually given in nm for visible light

Question 3

what is wavelength?

Answer 3

the distance between adjacent wave crests

Question 4

what is the symbol and unit of velocity in waves?

Answer 4

C and m s-1

Question 5

what is velocity?

Answer 5

the rate of advance of any one wave crest

Question 6

what is the symbol and unit of wavenumber?

Answer 6

V, m-1

Question 7

what does wavenumber represent?

Answer 7

number of waves in 1 metre of radiation

Question 8

what is the symbol and unit of frequency?

Answer 8

f, Hertz (Hz)

Question 9

what is frequency?

Answer 9

the number of wavelengths or cycles passing a point in 1 second

Question 10

what is the electromagnetic spectrum?

Answer 10

types of radiation arranged in order of wavelength

Question 11

what is the dual nature of electromagnetic radiation?

Answer 11

it behaves as both a wave and as a particle (photon)

Question 12

what is a photon?

Answer 12

a particle of electromagnetic radiation carrying quantised energy proportional to frequency

Question 13

what happens when a photon is absorbed?

Answer 13

energy is gained as electrons are promoted to a higher energy level

Question 14

what happens when a photon is emitted?

Answer 14

energy is lost as electrons drop to a lower energy level

Question 15

that one wavenumber energy equation

Answer 15

E = lhcv

Question 16

what is the energy unit of one mole of photons?

Answer 16

KJ mol-1

Question 17

what is absorption spectroscopy?

Answer 17

radiation is absorbed by atoms as electrons are promoted to higher energy levels

Question 18

what is emission spectroscopy?

Answer 18

radiation is emitted as excited electrons drop to lower energy levels

Question 19

how are absorption spectra produced?

Answer 19

by measuring how the intensity of absorbed light varies with wavelength

Question 20

how are emission spectra produced?

Answer 20

by meauring the intensity of light emitted at different wavelengths

Question 21

what do emission lines in atomic spectra provide evidence for?

Answer 21

discrete (quantised) energy levels in atoms

Question 22

what can absorption and emission spectra be used for?

Answer 22

to identify and quantify elements in a sample

Question 23

in atomic spectroscopy, what is the concentration of an element related to?

Answer 23

the intensity of light emitted or absorbed

Question 24

relationship between wavelength frequency and energy

Answer 24

as wavelength increases, frequency and energy decreases