1.1. Electromagnetic Radiation and Atomic Spectra Flashcards
What is the wavelength of a wave?
The distance between two crests of a wave. (measured in nanometres/ 10^-9 metres).
Define the frequency of a wave.
The number of wavelengths that pass a certain point in one second. (measured in Hertz/Hz)
What is the speed of electromagnetic radiation?
3x10^8 m/s
What does the symbol L stand for?
Avogadro’s constant.
What does the symbol ‘c’ stand for?
Velocity
What does the symbol ‘h’ stand for?
Planck’s constant.
When electromagnetic radiation acts more like particles than waves what are these particles called?
Photons.
What is the formula to calculate the energy carried by a photon?
E=hf
How do you convert J mol^-1 to kJ mol^-1?
Divide by 1000.
What is an atomic emission spectrum?
A coloured light obtained by passing high voltage electricity through a gas tube at low pressure. You can analyse this light by passing it through a prism. This light is diffracted and a series of lines is shown. These lines are the atomic emission spectrum of an atom/molecule.
What causes atomic emission spectra?
When an excited electron loses energy and jumps back down to either its ground state or a lower energy level and the lost energy is released in the form of photons. Each line corresponds to the energy given out when an excited electron moves to a lower energy state.
What causes atomic absorption spectra?
When the electrons are promoted an absorption spectrum is produced by measuring what wavelengths have been absorbed by the sample. This is also specific to a particular element.
What is a calibration graph?
It is a graph of which you can determine the amount of metal ions in a food stuff. It is when you use samples with known concentrations of the metal in question. The absorption is plotted against the concentration. We then can plot the unknown sample’s absorbance (which we can measure) against the concentration to find out the concentration.
