Relative Mass Flashcards
What is the standard isotope for relative mass?
Carbon-12
What are the units for atomic mass units?
u
How many atomic mass units are in a carbon-12 isotope?
12u
What is the standard mass for atomic mass?
1u
What is 1u equivalent to?
1/12 of an atom of carbon-12
What is 1u approximately the mass of?
A proton or neutron.
What is the relative isotopic mass?
The mass of an isotope relative to 1/12th of the mass of an atom of carbon-12.
What are the units for relative isotopic mass?
There are no units because it is a ratio between two masses.
What is the relative atomic mass?
This is the weighted mean mass of an atom of an element relative to 1/12th of the mass of an atom of carbon-12.
What is the abbreviation for relative atomic mass?
Ar
What does the weighed mean mass take into account?
The percentage abundance of each isotope.
The relative isotopic mass of each isotope.
What is used to find the % abundance of the isotopes in a sample of an element?
A mass spectrometer.
What does this mean: m/z?
This is the mass-to-charge ratio
How do you find m/z?
relative mass of ion/relative charge on ion
What happens to a sample in a mass spectrometer?
The sample is vaporised and then ionised.
What type of ions are formed in a mass spectrometer?
Positive ions.
What happens to the ions in the mass spectrometer?
They are accelerated.
What part of each isotope is separated?
The ions.
Why are the ions separated?
Heavier ions are harder to deflect than lighter ions.
How do you find the relative atomic mass of a sample?
(isotope mass number*%abundance)+(same again for next isotope)/100
What is the difference between ionic and covalent bonding?
In ionic bonding electrons are transferred.
In covalent bonding electrons are shared.
What does a displayed formula of a covalent.y bonded molecule show?
The relative position of atoms and the bonds between them as lines.
What are lone pairs?
Paired electrons that are not shared.
How are lone pairs shown in displayed formulas?
They are shown as dots (..).
Which molecule shows that predictions for bonding cannot be based solely on the noble gas electron structure?
BF3
What is mean by expansion of the octet?
When there are more electrons in the outer shell than in the nearest noble gas.
From which shell is expansion of the octet from?
N=3
