2.1-2.3, Atomic Structures, Masses, Ions & Isotopes
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What is the mass of a proton?
1
What is the mass of a neutron?
1
What is the mass of an electron?
1/1836
What is an ion?
An atom that has lost or gained electrons
What is an isotope?
An atom that has lost or gained neutrons
Do different isotopes of the same element react in the same or different way?
Same, because the number of neutrons has no effect on the reactions of an element
Do different isotopes of the same element have the same or different physical properties?
Isotopes will have small differences in physical properties (ie mp/bp) because they have differing masses.
What are the two types of ions?
Cations and anions
Are anions positive or negative?
Negative
Are cations positive or negative?
Positive
What is relative isotopic mass?
The mass of one isotope, compared with one-twelfth of the mass of an atom of Carbon-12. This is the weighted mean of all the isotopic masses.
What do you use to measure isotopic mass?
A mass spectrometer
How does a mass spectrometer measure relative masses?
By ionising particles, and then deflecting them with a magnetic field as they are accelerated. The amount of deflection depends on the m/z ratio of the ion and the detector records the number of ions of each mass detected.
When discussing m/z ratio, what does m stand for?
Relative Mass
When discussing m/z ratio, what does z stand for?
Charge
What are the uses of mass spectrometers?
• To measure the masses and abundances of the isotopes of an element and hence determine its relative atomic mass. • To measure the relative molecular mass of a compound.
What are all atoms’ and molecules’ masses measured against?
The carbon-12 isotope
How are atoms weighed?
By comparing their masses to eachother (relative masses)
What is relative molecular mass?
The weighted mean mass of a molecule, compared with one twelfth of the mass of an atom of carbon-12
What is relative formula mass?
The weighted mean mass of one formula unit of a substance compared with one twelfth of the mass of an atom of carbon-12
What are the units for relative masses?
There are no units, because it is a comparative measurement
Do metal ions have a positive or negative charge?
Positive charge
Do non-metal ions have a positive or negative charge?
Negative charge
What is a polyatomic ion?
An ion consisting of several atoms strongly bonded together, carrying an overall charge.