Mass Spectrometry

Created by: yasmin.ioa
Created on: 28-06-22 01:54

What is the name of a device that enables substances (elements or compounds) to be analysed by determining the masses of ions formed?

Time of flight (TOF) mass spectrometer.

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Explain the first stage of analysing a sample: electron spray ionisation.

A high-energy beam of electrons from the
electron gun removes the highest-energy (outer) electron from a molecule or an atom, forming a positively charged ion.

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What is this process called?
The positively charged ion is accelerated towards a negatively charged electrode, providing all ions with the same kinetic energy.

Acceleration.

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Explain the third stage of analysing a sample: ion drift.

The positively charged ions are electrostatically attracted to the negatively charged cathode.

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Explain the fourth stage of analysing a sample: ion detection and data analysis.

Ions of different masses are detected electronically and produce a small, varying electrical current that can be amplified and displayed on a computer. A mass spectrum is
produced.

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Name the four stages of analysing a sample to produce a mass spectrum.

1) Electron spray ionisation
2) Acceleration
3) Ion drift
4) Ion detection and data analysis

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What does the number of peaks in a mass spectrum mean?

The number of isotopes.

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How do you find the isotope with the highest abundance in a mass spectrum?

Find the highest peak.

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How do you calculate the relative atomic mass for an element using the mass spectrum?

By multiplying each mass number of each isotope by its abundance percentage (which is divided
by 100) and then adding them all together.

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On the horizontal axis, it reads "m/z". What does this mean?

Mass to charge ratio.

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What is measured on the vertical axis of a mass spectrum?

Relative abundance.

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You can calculate relative atomic mass (Ar) from a mass spectrum. What is relative atomic mass?

The weighted mean mass of an atom compared with 1/12 the mass of an atom of 12C.

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What is relative molecular mass?

The weighted mean mass of an molecule compared with 1/12 the mass of an atom of 12C.

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Other cards in this set

Card 2

Front

Explain the first stage of analysing a sample: electron spray ionisation.

Back

A high-energy beam of electrons from the
electron gun removes the highest-energy (outer) electron from a molecule or an atom, forming a positively charged ion.

Card 3

Front

What is this process called?
The positively charged ion is accelerated towards a negatively charged electrode, providing all ions with the same kinetic energy.

Back

Card 4

Front

Explain the third stage of analysing a sample: ion drift.

Back

Card 5

Front

Explain the fourth stage of analysing a sample: ion detection and data analysis.

Back

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Mass Spectrometry