1: Atomic Structure and the Periodic Table Flashcards
What is the atomic number?
Number of protons
What is the mass number?
Number of protons and neutrons
What is the relative mass of each particle?
Proton - 1
Neutron - 1
Electron- 0.0005
What is an isotope?
Atoms of the same element with different numbers of neutrons
What are the properties of isotopes?
Same chemical properties (same electrons)
Slightly different physical properties (mass of atom)
What is the relative atomic mass (Ar)?
Weighted mean mass of an atom of an element, compared to 1/12 of the mass of an atom of Carbon-12
Average of the relative isotopic masses
What is the relative isotopic mass?
Mass of an atom of an isotope compared to 1/12 of the mass of an atom of Carbon-12
Usually a whole number
What is the relative molecular mass?
Average mass of molecule compared to 1/12 of the mass of an atom of the carbon-12
What is the calculation for the relative atomic mass?
Multiply each isotopic mass by % abundance, add them up
Then divide by 100
What are mass spectrometers?
Devices which find out what samples are made up of by measuring the masses of their components
What do mass spectrometers produce?
Mass spectra
What is on the y-axis of a mass spectra?
Abundance of ions (percentage)
Height of peak gives relative isotopic abundance
What is on the x-axis of a mass spectra?
m/z
Mass/charge ratio, most charges are +1 so usually just relative isotopic masses
How would you work out the relative atomic mass using a mass spectra?
Multiply relative isotopic mass by abundance and add up results
Divide by sum of the isotopic abundances
What are the 4 stages of mass spectroscopy?
Ionisation
Acceleration
Deflection
Detection
What happens in the ionisation stage of mass spectroscopy?
Sample bombarded with high energy electrons (causes one electron removed from each atom of sample)
What happens in the acceleration stage of mass spectroscopy?
All particles in sample accelerated to same kinetic energy
What happens in the deflection stage of mass spectroscopy?
Electromagnet creates magnetic field which deflects ions different amounts based on their m/z
Smaller the m/z, the larger the deflection
What happens in the detection stage of mass spectroscopy?
Ions hit detector which creates a current
The current is detected, amplified and recorded
What fields is mass spectroscopy used?
Radioactive dating
Space research
Sport to detect illegal drugs
Pharmaceutical industry
How would you calculate the isotopic mass from relative atomic mass and 2/3 isotopic masses?
Work out % abundance of unknown
Using Ar of element and the other two isotopes work out mass of isotope
What is the M peak?
Molecular ion peak - peak with highest m/z vlaue
Occurs due to formation of the molecular ion from the ionisation process
What are the first 4 energy subshells?
s
p
d
f
What is an orbital?
Bit of space that electrons move in
Electrons in the subshell have the same energy
What can be held in each orbital?
2 electrons