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Define: Relative Atomic Mass
The average mass of an atom of an element, taking into account all of its naturally occuring isotopes, in comparison to 1/12 of the relative mass of an atom of carbon-12
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What are the advantages of high resolution mass spectrometry?
You can identify different molecules which have very similar Mr values.
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Why are atoms vapourised before entering the spectrometer?
To allow them to be ionised by the electron gun.
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How are atoms ionised in the mass spectrometer?
An electron gun knocks off an electron (rarely 2) from the outer levels of the gaseous atoms. This forms 1+ ions usually.
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How are ions accelerated in the mass spectrometer?
The ions are attracted to a negatively charged plate, and they therefore accelerate. The plate has a slit in it and therefore forms the ions into a straight beam.
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Describe the deflection phase of the mass spectrometer.
A magnetic field is at right angles to the direction of travel of the ions. This therefore deflects the positively charged ions around the corner, should they have the correct m/z ratio for that strength of magnetic field.
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How is an ion detected in the mass spectrometer?
The ion accepts electrons from the detector, therefore losing its positive charge. A current is produced which is proportional to the abundance of that ion in the sample.
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What is electronegativity?
The ability to attract the shared pair of electrons in a covalent bond.
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How does Electronegativity increase?
Diagonally up and accross the table.
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What does electronegativity depend on?
The nuclear charge (amount of protons) and the amount of sub-level shielding.
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Where are the s,p,d and f blocks?
Group 1+2 Metals, Non-metals, Transition Metals, Lanthanides and Actinides respectively.
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How does reactivity change down the s block?
They get more reactive.
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How does the reactivity of p-block elements change down the group?
The reactivity decreases down the group.
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What type of bonds do all metals form with one another?
Metallic bonds.
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What is the structure of silicon?
A giant covalent structure, similar to diamond.
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Why does the melting and boiling points of the metals increase from group 1-3?
The strength of metallic bonds increase as they give up more electrons and producing a higher charge difference.
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What affects the melting/boiling point of the elements in group 4-7?
The structure and therefore the vdw forces affect this. Silicon forms a giant covalent structure and so has no intermolecular forces, but requires a lot of energy to break many strong covalent bonds. Sulphur forms S8 and has a higher boiling point than P4 which has a higher boiling point than Cl2.
S>P>Cl
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Why do atomic radii decrease across the period?
The increased nuclear charge leads to a stronger attraction to its electrons, which therefore decreases the atomic radius.
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Why do the atomic radii increase down the group?
The outer main electron level is further away.
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First ionisation increases across the period. Why?
There is a stronger nuclear charge which leads to a stronger attraction to their electrons.
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