CHEMISTRY SPECTROSCOPY TEST SOLVED #15
Electromagnetic spectrum - correct answer Refers to all possible frequencies of
electromagnetic radiation shown in wavelength order. All forms of spectroscopy use a
part of the electromagnetic spectrum and utilise the fact that electromagnetic radiation
interacts with atoms and molecules.
Spectroscopic techniques provide information about: - correct answer - The type of
atom or molecule that is present (qualitative)
- How much of a particular atom or molecule is present (quantitative)
- The structure and bonding of a molecule
Flame tests - correct answer Metallic elements present in a compound are determined
by inserting a sample of compound into a Bunsen burner flame. The metal is identified
by comparing the flame colour with a list of characteristic colours produced by metals.
Electrons can jump to a higher energy level if it absorbs energy that corresponds
exactly to the difference in energy between the lower energy level and higher energy
level. For some metal atoms, the heat of the Bunsen flame provides sufficient energy for
this to happen.
Higher energy levels are unstable so the excited electrons quickly return to lower
energy levels, emitting the energy they had absorbed. If the energy emitted falls within
the band of energies visible to the eye, it can be seen as coloured light. The energy of a
photon of light emitted by an excited electron has a fixed value, equal to the difference
between the energy levels. The light consequently has a specific wavelength and
colour.
Atomic emission spectroscopy (AES) - correct answer An analytical technique that uses
light emission to measure the concentration and identity of a metal in a sample. Unlike
flame tests, it involves:
- Using a hotter flame, so that sufficient energy is available to excite electron in a wider
range of elements.
- Passing the light through a prism. The different energies in the light emitted by a
heated sample are separated into a series of coloured lines (an emission spectrum).
Each element has a different number of protons in the nucleus and the attraction of the
nucleus for electrons varies. No elements will have energy levels of exactly the same
energy, so each spectrum is characteristic of a particular element.
Atomic absorption spectroscopy (AAS) - correct answer An analytical technique that
uses light absorption to measure the concentration of a metal in a sample.
Because each element has a unique absorption spectrum, each element requires its
own light source that will emit light of the correct wavelength. This is provided by a
Electromagnetic spectrum - correct answer Refers to all possible frequencies of
electromagnetic radiation shown in wavelength order. All forms of spectroscopy use a
part of the electromagnetic spectrum and utilise the fact that electromagnetic radiation
interacts with atoms and molecules.
Spectroscopic techniques provide information about: - correct answer - The type of
atom or molecule that is present (qualitative)
- How much of a particular atom or molecule is present (quantitative)
- The structure and bonding of a molecule
Flame tests - correct answer Metallic elements present in a compound are determined
by inserting a sample of compound into a Bunsen burner flame. The metal is identified
by comparing the flame colour with a list of characteristic colours produced by metals.
Electrons can jump to a higher energy level if it absorbs energy that corresponds
exactly to the difference in energy between the lower energy level and higher energy
level. For some metal atoms, the heat of the Bunsen flame provides sufficient energy for
this to happen.
Higher energy levels are unstable so the excited electrons quickly return to lower
energy levels, emitting the energy they had absorbed. If the energy emitted falls within
the band of energies visible to the eye, it can be seen as coloured light. The energy of a
photon of light emitted by an excited electron has a fixed value, equal to the difference
between the energy levels. The light consequently has a specific wavelength and
colour.
Atomic emission spectroscopy (AES) - correct answer An analytical technique that uses
light emission to measure the concentration and identity of a metal in a sample. Unlike
flame tests, it involves:
- Using a hotter flame, so that sufficient energy is available to excite electron in a wider
range of elements.
- Passing the light through a prism. The different energies in the light emitted by a
heated sample are separated into a series of coloured lines (an emission spectrum).
Each element has a different number of protons in the nucleus and the attraction of the
nucleus for electrons varies. No elements will have energy levels of exactly the same
energy, so each spectrum is characteristic of a particular element.
Atomic absorption spectroscopy (AAS) - correct answer An analytical technique that
uses light absorption to measure the concentration of a metal in a sample.
Because each element has a unique absorption spectrum, each element requires its
own light source that will emit light of the correct wavelength. This is provided by a
