What are mass spectra used for?
To identify the molecular mass of an organic compound and to gain further information about its structure
What happens to an organic compound when it is places in the mass spectrometer?
It loses an electron and forms a positive ion - molecular ion
What does the mass spectrometer detect?
The mass to charge ratio of the molecular ion
What does the M+ peak on a mass spectrum indicate?
The molecular mass
Why may a small M+1 peak also be visible in a mass spectrum?
There is carbon present from the carbon-13 isotope which will give a larger molecular mass
What is the process of fragmentation?
When some molecular ions in the mass spectrometer break down into smaller fragments - causing fragment ions in the mass spectrum
What is the simplest way to break a molecular ion into a fragment ion?
The molecular ion is broken into a positively charged fragment ion and a radical
What common fragment ion can give an m/z peak at 15?
CH4+
What common fragment ion can give an m/z peak at 29?
C2H5+
What common fragment ion will give an m/z peak at 43?
C3H7+
What common fragment ion will give an m/z peak at 57?
C4H9+
What movements are in the covalent bonds between atoms in molecules?
They vibrate about a central point as the bonds possess energy
What happens when bonds absorb infrared radiation?
They bend or stretch more
Give the two types of vibration in a covalent bond?
A bend and a stretch
What happens when a bond is stretching?
A rhythmic movement along the line between the atoms so that the distance between the atomic centres is increasing and decreasing
What happens when a covalent bond bends?
The bond angle of the covalent bonds between atoms changes
What does the amount that a bond stretched or bends depend on?
The mass of the atoms in the bond
The strength of the Bond
How does the mass of an atom change how much a bond vibrates?
Heavier atoms vibrate slower than lighter atoms
How does the strength of the bond change how much a covalent bond vibrates?
Stronger bonds vibrate faster than weaker bonds
What must be the frequency of the radiation that the particular bond is absorbing?
Same as the natural frequency of the bond
What scale is used that is propoertional to frequency to measure the absorbed radiation?
Wave number
What happens to most of the sun’s visible light and IR radiation?
Passes through the atmosphere where it absorbed by the earth’s surface
If some of the sun’s visible light and IR radiation is re-emitted into the Earth’s atmosphere from the Earth’s surface what happens to the wavelength of that radiation?
It is re-emitted in the form of longer wavelength IR radiation
Name three abundant greenhouse gases that absorb longer-wavelength IR radiation
Methane, carbon dioxide and water vapour
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Chapter 5 - Covalent Bonding6
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Chapter 5 - Ionic Bonding12
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Chapter 5 - Electron Structure27
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Chapter 7 - The Periodic Table14
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Chapter 7 - Ionisation Energies14
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Chapter 7 - Periodic Trends In Structure And Bonding18
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Definitions43
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Chapter 6 - Shape Of Molecules And Ions12
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Chapter 6 - Electronegativity And Polarity3
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Module 4 - Organic Chem1
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Chapter 11 - Basic Concepts Of Organic Chemistry21
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Chapter 13 - Alkenes8
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Chapter 13 - Polymerisation In Alkenes19
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Chapter 930
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Chapter 8 - Reactivity Trends54
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Chapter 17 - Spectroscopy34
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Chapter 16 - Organic Synthesis10
